Patent Publication Number: US-9833242-B2

Title: Tissue thickness compensators

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application claiming priority under 35 U.S.C. §120 of U.S. patent application Ser. No. 13/433,167, entitled TISSUE THICKNESS COMPENSATORS, filed Mar. 28, 2012, now U.S. Pat. No. 9,220,501, which is a continuation-in-part application claiming priority under 35 U.S.C. §120 of U.S. patent application Ser. No. 13/097,891, entitled TISSUE THICKNESS COMPENSATOR FOR A SURGICAL STAPLER COMPRISING AN ADJUSTABLE ANVIL, filed on Apr. 29, 2011, which issued on Oct. 21, 2014 as U.S. Pat. No. 8,864,009, which is a continuation-in-part application claiming priority under 35 U.S.C. §120 of U.S. patent application Ser. No. 12/894,377, entitled SELECTIVELY ORIENTABLE IMPLANTABLE FASTENER CARTRIDGE, filed on Sep. 30, 2010, which issued on Mar. 12, 2013 as U.S. Pat. No. 8,393,514, the entire disclosures of which are hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     The present invention relates to surgical instruments and, in various embodiments, to surgical cutting and stapling instruments and staple cartridges therefor that are designed to cut and staple tissue. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a cross-sectional view of a surgical instrument embodiment; 
         FIG. 1A  is a perspective view of one embodiment of an implantable staple cartridge; 
         FIGS. 1B-1E  illustrate portions of an end effector clamping and stapling tissue with an implantable staple cartridge; 
         FIG. 2  is a partial cross-sectional side view of another end effector coupled to a portion of a surgical instrument with the end effector supporting a surgical staple cartridge and with the anvil thereof in an open position; 
         FIG. 3  is another partial cross-sectional side view of the end effector of  FIG. 2  in a closed position; 
         FIG. 4  is another partial cross-sectional side view of the end effector of  FIGS. 2 and 3  as the knife bar is starting to advance through the end effector; 
         FIG. 5  is another partial cross-sectional side view of the end effector of  FIGS. 2-4  with the knife bar partially advanced therethrough; 
         FIG. 6  is a perspective view of an alternative staple cartridge embodiment installed in a surgical cutting and stapling device; 
         FIG. 7  is a top view of the surgical staple cartridge and elongated channel of the device depicted in  FIG. 6 ; 
         FIG. 8  is a top view of another surgical staple cartridge embodiment installed in an elongated channel of an end effector; 
         FIG. 9  is a bottom view of an anvil; 
         FIG. 10  is a partial perspective view of a plurality of staples forming a portion of a staple line; 
         FIG. 11  is another partial perspective view of the staple line of  FIG. 10  with the staples thereof after being formed by being contacted by the anvil of the surgical cutting and stapling device; 
         FIG. 12  is a partial perspective view of alternative staples forming a portion of another staple line; 
         FIG. 13  is a partial perspective view of alternative staples forming a portion of another staple line; 
         FIG. 14  is a partial perspective view of alternative staples forming a portion of another staple line embodiment; 
         FIG. 15  is a cross-sectional view of an end effector supporting a staple cartridge; 
         FIG. 16  is a cross-sectional view of the elongated channel portion of the end effector of  FIG. 15  after the implantable staple cartridge body portion and staples have been removed therefrom; 
         FIG. 17  is a cross-sectional view of an end effector supporting another staple cartridge; 
         FIGS. 18A-18D  diagram the deformation of a surgical staple positioned within a collapsible staple cartridge body in accordance with at least one embodiment; 
         FIG. 19A  is a diagram illustrating a staple positioned in a crushable staple cartridge body; 
         FIG. 19B  is a diagram illustrating the crushable staple cartridge body of  FIG. 19A  being crushed by an anvil; 
         FIG. 19C  is a diagram illustrating the crushable staple cartridge body of  FIG. 19A  being further crushed by the anvil; 
         FIG. 19D  is a diagram illustrating the staple of  FIG. 19A  in a fully formed configuration and the crushable staple cartridge of  FIG. 19A  in a fully crushed condition; 
         FIG. 20  is a diagram depicting a staple positioned against a staple cartridge support surface and illustrating potential relative movement therebetween; 
         FIG. 21  is a cross-sectional view of a staple cartridge support surface comprising a slot, or trough, configured to stabilize the base of the staple of  FIG. 20 ; 
         FIG. 22  is a cross-sectional view of a staple comprising an overmolded crown and a slot, or trough, configured to receive a portion of the crown in accordance with at least one alternative embodiment; 
         FIG. 23  is a top view of a staple cartridge in accordance with at least one embodiment comprising staples embedded in a collapsible staple cartridge body; 
         FIG. 24  is an elevational view of the staple cartridge of  FIG. 23 ; 
         FIG. 25  is an elevational view of a staple cartridge in accordance with at least one embodiment comprising a protective layer surrounding staples positioned within a collapsible staple cartridge body; 
         FIG. 26  is a cross-sectional view of the staple cartridge of  FIG. 25  taken along line  26 - 26  in  FIG. 25 ; 
         FIG. 27  is an elevational view of a staple cartridge in accordance with at least one embodiment comprising staples at least partially extending outside of a collapsible staple cartridge body and a protective layer surrounding the staple cartridge body; 
         FIG. 28  is a cross-sectional view of the staple cartridge of  FIG. 27  taken along line  28 - 28  in  FIG. 27 ; 
         FIG. 29  is a partial break-away view of a staple cartridge in accordance with at least one embodiment comprising staples at least partially embedded in a collapsible staple cartridge body, the staples being at least partially positioned in a staple cavity void in the staple cartridge body; 
         FIG. 30  is a cross-sectional view of the staple cartridge of  FIG. 29  taken along line  30 - 30  in  FIG. 29 ; 
         FIG. 31  is a partial break-away view of a staple cartridge in accordance with at least one embodiment; 
         FIG. 32  is a partial break-away view of a staple cartridge in accordance with at least one embodiment comprising staples at least partially embedded within a collapsible staple cartridge body and an alignment matrix connecting the staples and aligning the staples with respect to each other; 
         FIG. 33  is a cross-sectional view of the staple cartridge of  FIG. 32  taken along line  33 - 33  in  FIG. 32 ; 
         FIG. 34  is partial cut-away view of an inner layer of a compressible staple cartridge body; 
         FIG. 35  is a diagram illustrating the inner layer of  FIG. 34  compressed between a transfer plate and a support plate; 
         FIG. 36  is a diagram illustrating staples being inserted into the compressed inner layer of  FIG. 35 ; 
         FIG. 37  is a diagram of the support plate of  FIG. 35  being removed away from the inner layer; 
         FIG. 38  is a diagram of a subassembly comprising the inner layer of  FIG. 34  and the staples of  FIG. 36  being inserted into an outer layer; 
         FIG. 39  is a diagram illustrating the outer layer of  FIG. 38  being sealed to form a sealed staple cartridge; 
         FIG. 40  is a cross-sectional view of the sealed staple cartridge of  FIG. 39 ; 
         FIG. 41  is a cross-sectional view of a staple cartridge and staple cartridge channel in accordance with at least one embodiment; 
         FIG. 42  is a diagram illustrating a portion of the staple cartridge of  FIG. 41  in a deformed state; 
         FIG. 43  is an elevational view of an end effector of a surgical stapler comprising an anvil in an open position and a staple cartridge positioned within a staple cartridge channel; 
         FIG. 44  is an elevational view of the end effector of  FIG. 43  illustrating the anvil in a closed position and the staple cartridge compressed between the anvil and the staple cartridge channel; 
         FIG. 45  is an elevational view of the end effector of  FIG. 43  illustrating the staple cartridge of  FIG. 43  positioned within the staple cartridge channel in an alternative manner; 
         FIG. 46  is a cross-sectional view of an end effector of a surgical stapler comprising a compressible staple cartridge positioned within a staple cartridge channel and a piece of buttress material attached to an anvil; 
         FIG. 47  is a cross-sectional view of the end effector of  FIG. 46  illustrating the anvil in a closed position; 
         FIG. 48  is a cross-sectional view of an alternative embodiment of an end effector of a surgical stapler comprising a staple cartridge comprising a water impermeable layer; 
         FIG. 49  is a cross-sectional view of another alternative embodiment of an end effector of a surgical stapler; 
         FIG. 50  is a cross-sectional view of an alternative embodiment of an end effector of a surgical stapler comprising a stepped anvil and a staple cartridge comprising a stepped cartridge body; 
         FIG. 51  is a cross-sectional view of another alternative embodiment of an end effector of a surgical stapler; 
         FIG. 52  is a cross-sectional view of an alternative embodiment of an end effector of a surgical stapler comprising inclined tissue-contacting surfaces; 
         FIG. 53  is a cross-sectional view of another alternative embodiment of an end effector of a surgical stapler comprising inclined tissue-contacting surfaces; 
         FIG. 54  is a cross-sectional view of an alternative embodiment of an end effector of a surgical stapler comprising a support insert configured to support a staple cartridge; 
         FIG. 55  is a cross-sectional view of an alternative embodiment of an end effector of a surgical stapler comprising a staple cartridge comprising a plurality of compressible layers; 
         FIG. 56  is a cross-sectional view of an alternative embodiment of an end effector of a surgical stapler comprising a staple cartridge comprising a stepped compressible cartridge body; 
         FIG. 57  is a cross-sectional view of another alternative embodiment of an end effector of a surgical stapler comprising a staple cartridge comprising a stepped compressible cartridge body; 
         FIG. 58  is a cross-sectional view of an alternative embodiment of an end effector of a surgical stapler comprising a staple cartridge comprising a curved tissue-contacting surface; 
         FIG. 59  is a cross-sectional view of an alternative embodiment of an end effector of a surgical stapler comprising a staple cartridge having an inclined tissue-contacting surface; 
         FIG. 60  is a cross-sectional view of a compressible staple cartridge comprising staples and at least one medicament stored therein; 
         FIG. 61  is a diagram illustrating the compressible staple cartridge of  FIG. 60  after it has been compressed and the staples contained therein have been deformed; 
         FIG. 62  is a partial cut-away view of a staple cartridge in accordance with at least one embodiment; 
         FIG. 63  is a cross-sectional view of the staple cartridge of  FIG. 62 ; 
         FIG. 64  is a perspective view of an implanted staple cartridge in accordance with at least one alternative embodiment; 
         FIG. 65  is a cross-sectional view of the implanted staple cartridge of  FIG. 64 ; 
         FIG. 66  is a perspective view of an alternative embodiment of a staple cartridge comprising deformable members extending from an outer layer of the staple cartridge; 
         FIG. 67  is a perspective view of an alternative embodiment of a staple cartridge comprising an outer layer of the staple cartridge being assembled to an inner layer; 
         FIG. 68  is a cross-sectional view of an alternative embodiment of a staple cartridge comprising a plurality of staples, a compressible layer, and a pledget layer; 
         FIG. 69  is a perspective view of the pledget layer of  FIG. 68 ; 
         FIG. 70  is a perspective view of a pledget singulated from the pledget layer of  FIG. 68  and a staple aligned with a groove in the pledget; 
         FIG. 71  is a perspective view of two connected pledgets from the pledget layer of  FIG. 68 ; 
         FIG. 72  is a perspective view of a pledget support frame of the pledget layer of  FIG. 68  being removed from the singulated pledgets; 
         FIG. 73  is an exploded perspective view of an alternative embodiment of a compressible staple cartridge comprising staples therein and a system for driving the staples against an anvil; 
         FIG. 73A  is a partial cut-away view of an alternative embodiment of the staple cartridge of  FIG. 73 ; 
         FIG. 74  is a cross-sectional view of the staple cartridge of  FIG. 73 ; 
         FIG. 75  is an elevational view of a sled configured to traverse the staple cartridge of  FIG. 73  and move the staples to toward the anvil; 
         FIG. 76  is a diagram of a staple driver which can be lifted toward the anvil by the sled of  FIG. 75 ; 
         FIG. 77  is a break-away view of a staple cartridge in accordance with at least one alternative embodiment comprising staples positioned within staple drivers; 
         FIG. 78  is a cross-sectional view of the staple cartridge of  FIG. 77  positioned within a staple cartridge channel; 
         FIG. 79  is a cross-sectional view of the staple cartridge of  FIG. 77  illustrating an anvil moved into a closed position and staples contained within the staple cartridge deformed by the anvil; 
         FIG. 80  is a cross-sectional view of the staple cartridge of  FIG. 77  illustrating the staples moved upwardly toward the anvil; 
         FIG. 81  is a perspective view of an alternative embodiment of a staple cartridge comprising straps connecting the flexible sides of the staple cartridge; 
         FIG. 82  is a perspective view of a sled and cutting member assembly; 
         FIG. 83  is a diagram of the sled and cutting member assembly of  FIG. 82  being used to lift the staples of the staple cartridge of  FIG. 77 ; 
         FIG. 84  is a diagram illustrating a sled configured to engage and lift staples toward an anvil and a lock-out system configured to selectively permit the sled to move distally; 
         FIGS. 85A-85C  illustrate the progression of a staple being inserted into a staple crown; 
         FIG. 86  is a cross-sectional view of a staple cartridge comprising a support pan or retainer; 
         FIG. 87  is a partial cross-sectional view of a compressible staple cartridge in accordance with at least one alternative embodiment; 
         FIG. 88  is a diagram illustrating the staple cartridge of  FIG. 87  in an implanted condition; 
         FIG. 89  is a partial cut-away view of a compressible staple cartridge in accordance with at least one alternative embodiment; 
         FIG. 90  is a partial cross-sectional view of the staple cartridge of  FIG. 89 ; 
         FIG. 91  is a diagram illustrating the staple cartridge of  FIG. 89  in an implanted condition; 
         FIG. 92  is a partial cross-sectional view of a crushable staple cartridge in accordance with at least one alternative embodiment; 
         FIG. 93  is a partial cut-away view of a collapsible staple cartridge in accordance with at least one embodiment comprising a plurality of collapsible elements; 
         FIG. 94  is a perspective view of a collapsible element of  FIG. 93  in an uncollapsed state; 
         FIG. 95  is a perspective view of the collapsible element of  FIG. 94  in a collapsed state; 
         FIG. 96A  is a partial cross-sectional view of an end effector of a surgical stapling instrument comprising a jaw, a staple cartridge channel positioned opposite the jaw, and a staple cartridge positioned within the staple cartridge channel, wherein the jaw comprises a retention matrix attached thereto; 
         FIG. 96B  is a partial cross-sectional view of the end effector of  FIG. 96A  illustrating the jaw being moved toward the staple cartridge channel, the staple cartridge being compressed by the anvil and the retention matrix, and a staple at least partially extending through tissue positioned intermediate the retention matrix and the staple cartridge; 
         FIG. 96C  is a partial cross-sectional view of the end effector of  FIG. 96A  illustrating the jaw in a final position and the retention matrix engaged with the staple of  FIG. 96B ; 
         FIG. 96D  is a partial cross-sectional view of the end effector of  FIG. 96A  illustrating the jaw and the staple cartridge channel being moved away from the implanted staple cartridge and retention matrix; 
         FIG. 97  is a perspective view of a retention aperture of a retention matrix in accordance with at least one alternative embodiment comprising a plurality of retention members configured to engage a fastener leg extending therethrough; 
         FIG. 98  is a perspective view of a retention aperture of a retention matrix in accordance with at least one alternative embodiment comprising six retention members; 
         FIG. 99  is a perspective view of a retention aperture of a retention matrix in accordance with at least one alternative embodiment comprising eight retention members; 
         FIG. 100  is a perspective view of a retention aperture of a retention matrix in accordance with at least one alternative embodiment comprising a plurality of retention members configured to engage a fastener leg extending therethrough; 
         FIG. 101  is a perspective view of a retention aperture of a retention matrix in accordance with at least one alternative embodiment comprising six retention members; 
         FIG. 102  is a perspective view of a retention aperture of a retention matrix in accordance with at least one alternative embodiment comprising eight retention members; 
         FIG. 103  is a perspective view of a retention aperture of a retention matrix in accordance with at least one alternative embodiment comprising a plurality of retention members that have been stamped from a sheet of metal; 
         FIG. 104  is a perspective view of a retention aperture of a retention matrix in accordance with at least one alternative embodiment comprising a plurality of apertures extending around the perimeter of the retention aperture; 
         FIG. 105  is a top view of a retention aperture of a retention matrix in accordance with at least one alternative embodiment; 
         FIG. 106  is a top view of a retention aperture of a retention matrix in accordance with at least one alternative embodiment; 
         FIG. 107  is a top view of a retention aperture of a retention matrix in accordance with at least one alternative embodiment; 
         FIG. 108  is a top view of a retention aperture of a retention matrix in accordance with at least one alternative embodiment; 
         FIG. 109  is a top view of a retention aperture of a retention matrix in accordance with at least one alternative embodiment; 
         FIG. 110  is a top view of a retention aperture of a retention matrix comprising a retention tab extending into the retention aperture in accordance with at least one embodiment; 
         FIG. 111  is a top view of a retention aperture of a retention matrix comprising a retention tab extending into the retention aperture in accordance with at least one alternative embodiment; 
         FIG. 112  is a perspective view of a fastening system comprising a plurality of staples, a retention matrix engaged with the staples, and an alignment matrix configured to align the staples; 
         FIG. 113  is a perspective view of the retention matrix of  FIG. 112 ; 
         FIG. 114  is a perspective view of the alignment matrix of  FIG. 112 ; 
         FIG. 115  is a partial top view of the retention matrix of  FIG. 112  engaged with the staples of  FIG. 112 ; 
         FIG. 116  is a partial bottom view of the retention matrix of  FIG. 112  engaged with the staples of  FIG. 112 ; 
         FIG. 117  is a partial elevational view of the fastening system of  FIG. 112 ; 
         FIG. 118  is a partial perspective view of the fastening system of  FIG. 112 ; 
         FIG. 119  is a partial cross-sectional view of the retention matrix of  FIG. 112  engaged with the staples of  FIG. 112 ; 
         FIG. 120  is a partial cross-sectional view of the fastening system of  FIG. 112 ; 
         FIG. 121  is a perspective view of the fastening system of  FIG. 112  further comprising protective caps assembled to the legs of the staples; 
         FIG. 122  is a bottom perspective view of the fastening system arrangement of  FIG. 121 ; 
         FIG. 123  is a partial perspective view of the fastening system arrangement of  FIG. 121 ; 
         FIG. 124  is a partial cross-sectional view of the fastening system arrangement of  FIG. 121 ; 
         FIG. 125  is an elevational view of an end effector in accordance with at least one embodiment comprising a jaw in an open position, a retention matrix and a plurality of protective caps positioned in the jaw, and a staple cartridge positioned in a staple cartridge channel; 
         FIG. 126  is an elevational view of the end effector of  FIG. 125  in a closed position; 
         FIG. 127  is an elevational view of the end effector of  FIG. 125  in a fired position; 
         FIG. 128  is an elevational view of the retention matrix and protective caps of  FIG. 125  assembled to the staple cartridge of  FIG. 125 ; 
         FIG. 129  is a detail view of the arrangement of  FIG. 128 ; 
         FIG. 130  is an elevational view of the end effector of  FIG. 125  illustrating the jaw in an open position with thinner tissue positioned between the retention matrix and the staple cartridge; 
         FIG. 131  is an elevational view of the end effector of  FIG. 125  illustrating the jaw in a closed position against the thinner tissue of  FIG. 130 ; 
         FIG. 132  is an elevational view of the end effector of  FIG. 125  illustrating the jaw in a fired position to capture the thinner tissue of  FIG. 130  between the retention matrix and the staple cartridge; 
         FIG. 133  is an elevational view of the retention matrix and the protective caps of  FIG. 125  assembled to the staple cartridge of  FIG. 125  with the thin tissue of  FIG. 130  positioned therebetween; 
         FIG. 134  is a detail view of the arrangement of  FIG. 133 ; 
         FIG. 135  is a cross-sectional view of a protective cap positioned on the tip of a staple leg in accordance with at least one alternative embodiment; 
         FIG. 136  is a perspective view of a plurality of protective caps embedded within a sheet of material; 
         FIG. 137  is a perspective view of a jaw comprising a plurality of recesses configured to receive a plurality of protective caps therein; 
         FIG. 138  is a detail view of a portion of a jaw comprising a sheet covering the protective caps positioned within the jaw of  FIG. 137 ; 
         FIG. 139  is a cross-sectional view of a protective cap positioned on a tip of a staple leg in accordance with at least one alternative embodiment wherein the protective cap comprises an interior forming surface; 
         FIG. 140  is another cross-sectional view of the protective cap of  FIG. 139  illustrating the staple leg being deformed against the forming surface; 
         FIG. 141  is a top view of an alternative embodiment of a retention matrix comprising a plurality of connected matrix elements; 
         FIG. 142  is a top view of an alternative embodiment of a retention matrix comprising a plurality of connected matrix elements; 
         FIG. 143  is a top view of an alternative embodiment of a retention matrix comprising a plurality of connected matrix elements; 
         FIG. 144  is a top view of an alternative embodiment of an array of retention matrices comprising a plurality of connected matrix elements; 
         FIG. 145  is a top view of an alternative embodiment of a retention matrix comprising a plurality of connected matrix elements; 
         FIG. 146  is a partial exploded view of a jaw comprising a retention matrix including a compressible cover; 
         FIG. 147  is a detail view of the retention matrix of  FIG. 146 ; 
         FIG. 148  is a partial cross-sectional view of a fastening system comprising a retention matrix including a compressible layer and a plurality of cells encapsulating one or more medicaments; 
         FIG. 149  is a diagram illustrating staple legs which have pierced the cells of  FIG. 148  as they are being engaged with the retention matrix; 
         FIG. 150  is a partial cross-sectional view of a fastening system comprising a retention matrix including a compressible layer; 
         FIG. 151  is an elevational view of a fastener cartridge insertion assembly comprising a holder, a first fastener cartridge, and a second fastener cartridge; 
         FIG. 152  is an elevational view of an end effector of a surgical stapler comprising a first jaw and a second jaw, the second jaw being illustrated in an open configuration; 
         FIG. 153  is an elevational view of the end effector of  FIG. 152  illustrating the second jaw in a closed configuration and the fastener cartridge insertion assembly of  FIG. 151  being used to load the first jaw with the first cartridge and the second jaw with the second cartridge; 
         FIG. 154  is an elevational view of the loaded end effector of  FIG. 153  illustrating the cartridge insertion assembly removed from the end effector, the second jaw in an open configuration once again, and tissue positioned intermediate the first jaw and the second jaw; 
         FIG. 155  is an elevational view of the loaded end effector of  FIG. 154  in a fired configuration; 
         FIG. 156  is an elevational view of the first cartridge and the second cartridge in an implanted condition; 
         FIG. 157  is an elevational view of the end effector of  FIG. 152  illustrating a portion of the first cartridge still engaged with the first jaw in accordance with at least one embodiment; 
         FIG. 158  is an elevational view of an alternative embodiment of a fastener cartridge insertion assembly comprising a holder, a first fastener cartridge, and a second fastener cartridge; 
         FIG. 159  is an elevational view of the fastener cartridge insertion assembly of  FIG. 158  being used to load a first jaw of an end effector with the first cartridge and a second jaw with the second cartridge; 
         FIG. 160  is a cross-sectional view of the loaded end effector of  FIG. 159 ; 
         FIG. 161  is a perspective view of a surgical stapler comprising a bottom jaw and a top jaw in accordance with at least one embodiment illustrated with portions of the surgical stapler removed; 
         FIG. 162  is a perspective view of the surgical stapler of  FIG. 161  with the top jaw removed; 
         FIG. 163  is a perspective view of a slidable anvil system of the top jaw of the surgical stapler of  FIG. 161  comprising a first slidable anvil and a second slidable anvil; 
         FIG. 164  is an end view of the slidable anvil system of  FIG. 163 ; 
         FIG. 165  is a top view of the slidable anvil system of  FIG. 163 ; 
         FIG. 166  is a diagram illustrating the slidable anvil system of  FIG. 163  in an unfired condition; 
         FIG. 167  is a diagram illustrating the first slidable anvil of the slidable anvil system of  FIG. 163  in an unfired position and staples positioned within the bottom jaw in an undeployed position; 
         FIG. 168  is a diagram illustrating the staples in the bottom jaw in a deployed configuration and the first slidable anvil of  FIG. 167  being pulled proximally to deform a first group of staple legs of the staples; 
         FIG. 169  is a diagram illustrating the first group of staples of  FIG. 168  deformed to a fully deformed state; 
         FIG. 170  is a diagram illustrating the second slidable anvil of the slidable anvil system of  FIG. 163  being pushed distally to deform a second group of staple legs; 
         FIG. 171  is a partial perspective view of an anvil comprising a plurality of forming pockets in at least one embodiment; 
         FIG. 172  is a cross-sectional end view of the anvil of  FIG. 171 ; 
         FIG. 173  is a diagram illustrating a first step in manufacturing the forming pockets of  FIG. 171 ; 
         FIG. 174  is a diagram illustrating a second step in manufacturing the forming pockets of  FIG. 171 ; 
         FIG. 175  is a top view of the forming pocket arrangement of the anvil of  FIG. 171 ; 
         FIG. 176  is a diagram illustrating a first step of a manufacturing process for producing an anvil; 
         FIG. 177  is a diagram illustrating a second step in the manufacturing process of  FIG. 176 ; 
         FIG. 178  is a diagram illustrating a third step in the manufacturing process of  FIG. 176 ; 
         FIG. 179  is a left front perspective view of a surgical stapling and severing instrument with a handle portion including a link triggered automatic retraction and a ratcheting manual retraction mechanism; 
         FIG. 180  is a right aft perspective view of the surgical stapling and severing instrument of  FIG. 179  with a portion of an elongate shaft cut away and a right half shell of a handle housing removed to expose an automatic end-of-firing travel retraction mechanism and a manual firing retraction mechanism; 
         FIG. 181  is a right aft perspective disassembled view of the handle portion and an elongate shaft of the surgical stapling and severing instrument of  FIG. 179 ; 
         FIG. 182  is a right aft perspective view of the surgical stapling and severing instrument of  FIG. 31  with a right half shell and outer portions of the implement portion removed to expose the closure and firing mechanisms in an initial state; 
         FIG. 183  is a right side view in elevation of the partially disassembled surgical stapling and severing instrument of  FIG. 182 ; 
         FIG. 184  is a right aft perspective view of the partially disassembled surgical stapling and severing instrument of  FIG. 182  with a closure mechanism closed and clamped and the side pawl firing mechanism completing a first stroke and with a manual retraction mechanism removed to expose a distal link of the linked rack that triggers automatic retraction of the firing mechanism; 
         FIG. 185  is a right aft perspective view of the partially disassembled surgical stapling and severing instrument of  FIG. 183  with the side pawl firing mechanism disengaged and the distal link approaching automatic retraction; 
         FIG. 186  is left side view in elevation of the partially disassembled surgical stapling and severing instrument of  FIG. 183  in an initial state of end effector open and anti-backup mechanism engaged; 
         FIG. 187  is a left side detail view of the right half shell and an anti-backup release lever of the handle portion of  FIG. 186 ; 
         FIG. 188  is a left side detail view in elevation of the disassembled surgical stapling and severing instrument of  FIG. 179  with the closure trigger clamped, the firing trigger performing a final stroke and the distal link positioned to trip automatic retraction; 
         FIG. 189  is a left side detail in elevation of the disassembled surgical stapling and severing instrument of  FIG. 188  immediately after the distal link has actuated and locked forward the anti-backup release lever, allowing the linked rack to retract; 
         FIG. 190  is a right disassembled perspective view of the idler and aft gears and manual retraction lever and ratcheting pawl of a manual retraction mechanism of the surgical stapling and severing instrument of  FIG. 179 ; 
         FIG. 191  is a right perspective view of the manual retraction mechanism of  FIG. 190  with the manual retraction lever partially cut away to expose a smaller diameter ratchet gear on the aft gear engaging the ratcheting pawl; 
         FIG. 192  is a partially disassembled left side view in elevation of a surgical stapling and severing instrument of  FIG. 179  with the anti-backup mechanism engaged to a fully fired linked rack that is disconnected from a combination tension/compression spring prior to actuation of the manual retraction lever of  FIG. 190 ; 
         FIG. 193  is a partially disassembled left side view in elevation of the surgical stapling and severing instrument of  FIG. 192  with hidden portions of the anti-backup release lever, aft gear, and manual firing release lever shown in phantom; 
         FIG. 194  is a partially disassembled left side view in elevation of the surgical stapling and severing instrument of  FIG. 193  after actuation of the manual firing release lever has manually retracted the link rack; 
         FIG. 195  is a partially disassembled left side view in elevation of the surgical stapling and severing instrument of  FIG. 194  with the linked rack omitted depicting the manual firing release lever disengaging the anti-backup mechanism; 
         FIG. 196  is a left side detail view of an alternative anti-backup release lever and handle housing for the surgical stapling and severing instrument of  FIG. 179 ; 
         FIG. 197  is a left perspective disassembled view of the alternative anti-backup release lever, aft gear axle, and automatic retraction cam wheel of  FIG. 196 ; 
         FIG. 198  is a right side view in elevation of the alternative anti-backup release mechanism of  FIG. 196  with the linked rack in a retracted position and the anti-backup release lever proximally positioned with the anti-backup plate engaged to the firing rod; 
         FIG. 198A  is a right detail side view in elevation of the aft gear, automatic retraction cam wheel and distal-most link of  FIG. 198 ; 
         FIG. 199  is a right side view in elevation of the anti-backup release mechanism of  FIG. 198  after a first firing stroke; 
         FIG. 199A  is a right detail side view in elevation of the aft gear, automatic retraction cam wheel and a second link of  FIG. 199 ; 
         FIG. 200  is a right side view in elevation of the anti-backup release mechanism of  FIG. 199  after a second firing stroke; 
         FIG. 200A  is a right detail side view in elevation of the aft gear, automatic retraction cam wheel and third link of  FIG. 200 ; 
         FIG. 201  is a right detail side view in elevation of the anti-backup release mechanism of  FIG. 200  after a third firing and final stroke; 
         FIG. 201A  is a right detail side view in elevation of the aft gear, automatic retraction cam wheel and proximal-most fourth link of  FIG. 201 ; 
         FIG. 202  is a right side view in elevation of the automatic release mechanism of  FIG. 201  after a further firing stroke causes the automatic retraction cam wheel to distally slide and lock the anti-backup release lever, disengaging the anti-backup mechanism; 
         FIG. 203  is a left, front perspective view of an open staple applying assembly with a right half portion of a replaceable staple cartridge included in a staple channel; 
         FIG. 204  is an exploded perspective view of the staple applying assembly of  FIG. 203  with a complete replaceable staple cartridge and an nonarticulating shaft configuration; 
         FIG. 205  is a perspective view of a two-piece knife and firing bar (“E-beam”) of the staple applying assembly of  FIG. 203 ; 
         FIG. 206  is a perspective view of a wedge sled of a staple cartridge of a staple applying assembly; 
         FIG. 207  is a left side view in elevation taken in longitudinal cross section along a centerline line  207 - 207  of the staple applying assembly of  FIG. 203 ; 
         FIG. 208  is a perspective view of the open staple applying assembly of  FIG. 203  without the replaceable staple cartridge, a portion of the staple channel proximate to a middle pin of two-piece knife and firing bar, and without a distal portion of a staple channel; 
         FIG. 209  is a front view in elevation taken in cross section along line  209 - 209  of the staple applying assembly of  FIG. 203  depicting internal staple drivers of the staple cartridge and portions of the two-piece knife and firing bar; 
         FIG. 210  is a left side view in elevation taken generally along the longitudinal axis of line  207 - 207  of a closed staple applying assembly of  FIG. 203  to include center contact points between the two-piece knife and wedge sled but also laterally offset to show staples and staple drivers within the staple cartridge; 
         FIG. 211  is a left side detail view in elevation of the staple applying assembly of  FIG. 210  with the two-piece knife retracted slightly more as typical for staple cartridge replacement; 
         FIG. 212  is a left side detail view in elevation of the staple applying assembly of  FIG. 211  with the two-piece knife beginning to fire, corresponding to the configuration depicted in  FIG. 210 ; 
         FIG. 213  is a left side cross-sectional view in elevation of the closed staple applying assembly of  FIG. 210  after the two-piece knife and firing bar has distally fired; 
         FIG. 214  is a left side cross-sectional view in elevation of the closed staple applying assembly of  FIG. 213  after firing of the staple cartridge and retraction of the two-piece knife; 
         FIG. 215  is a left side cross-sectional detail view in elevation of the staple applying assembly of  FIG. 214  with the two-piece knife allowed to drop into a lockout position; 
         FIG. 216  is a perspective view of a staple cartridge comprising a rigid support portion and a compressible tissue thickness compensator for use with a surgical stapling instrument in accordance with at least one embodiment of the invention; 
         FIG. 217  is a partially exploded view of the staple cartridge of  FIG. 216 ; 
         FIG. 218  is a fully exploded view of the staple cartridge of  FIG. 216 ; 
         FIG. 219  is another exploded view of the staple cartridge of  FIG. 216  without a warp covering the tissue thickness compensator; 
         FIG. 220  is a perspective view of a cartridge body, or support portion, of the staple cartridge of  FIG. 216 ; 
         FIG. 221  is a top perspective view of a sled movable within the staple cartridge of  FIG. 216  to deploy staples from the staple cartridge; 
         FIG. 222  is a bottom perspective view of the sled of  FIG. 221 ; 
         FIG. 223  is an elevational view of the sled of  FIG. 221 ; 
         FIG. 224  is a top perspective view of a driver configured to support one or more staples and to be lifted upwardly by the sled of  FIG. 221  to eject the staples from the staple cartridge; 
         FIG. 225  is a bottom perspective view of the driver of  FIG. 224 ; 
         FIG. 226  is a wrap configured to at least partially surround a compressible tissue thickness compensator of a staple cartridge; 
         FIG. 227  is a partial cut away view of a staple cartridge comprising a rigid support portion and a compressible tissue thickness compensator illustrated with staples being moved from an unfired position to a fired position during a first sequence; 
         FIG. 228  is an elevational view of the staple cartridge of  FIG. 227 ; 
         FIG. 229  is a detail elevational view of the staple cartridge of  FIG. 227 ; 
         FIG. 230  is a cross-sectional end view of the staple cartridge of  FIG. 227 ; 
         FIG. 231  is a bottom view of the staple cartridge of  FIG. 227 ; 
         FIG. 232  is a detail bottom view of the staple cartridge of  FIG. 227 ; 
         FIG. 233  is a longitudinal cross-sectional view of an anvil in a closed position and a staple cartridge comprising a rigid support portion and a compressible tissue thickness compensator illustrated with staples being moved from an unfired position to a fired position during a first sequence; 
         FIG. 234  is another cross-sectional view of the anvil and the staple cartridge of  FIG. 233  illustrating the anvil in an open position after the firing sequence has been completed; 
         FIG. 235  is a partial detail view of the staple cartridge of  FIG. 233  illustrating the staples in an unfired position; 
         FIG. 236  is a cross-sectional elevational view of a staple cartridge comprising a rigid support portion and a compressible tissue thickness compensator illustrating the staples in an unfired position; 
         FIG. 237  is a detail view of the staple cartridge of  FIG. 236 ; 
         FIG. 238  is an elevational view of an anvil in an open position and a staple cartridge comprising a rigid support portion and a compressible tissue thickness compensator illustrating the staples in an unfired position; 
         FIG. 239  is an elevational view of an anvil in a closed position and a staple cartridge comprising a rigid support portion and a compressible tissue thickness compensator illustrating the staples in an unfired position and tissue captured between the anvil and the tissue thickness compensator; 
         FIG. 240  is a detail view of the anvil and staple cartridge of  FIG. 239 ; 
         FIG. 241  is an elevational view of an anvil in a closed position and a staple cartridge comprising a rigid support portion and a compressible tissue thickness compensator illustrating the staples in an unfired position illustrating thicker tissue positioned between the anvil and the staple cartridge; 
         FIG. 242  is a detail view of the anvil and staple cartridge of  FIG. 241 ; 
         FIG. 243  is an elevational view of the anvil and staple cartridge of  FIG. 241  illustrating tissue having different thicknesses positioned between the anvil and the staple cartridge; 
         FIG. 244  is a detail view of the anvil and staple cartridge of  FIG. 241  as illustrated in  FIG. 243 ; 
         FIG. 245  is a diagram illustrating a tissue thickness compensator which is compensating for different tissue thickness captured within different staples; 
         FIG. 246  is a diagram illustrating a tissue thickness compensator applying a compressive pressure to one or more vessels that have been transected by a staple line; 
         FIG. 247  is a diagram illustrating a circumstance wherein one or more staples have been improperly formed; 
         FIG. 248  is a diagram illustrating a tissue thickness compensator which could compensate for improperly formed staples; 
         FIG. 249  is a diagram illustrating a tissue thickness compensator positioned in a region of tissue in which multiple staples lines have intersected; 
         FIG. 250  is a diagram illustrating tissue captured within a staple; 
         FIG. 251  is a diagram illustrating tissue and a tissue thickness compensator captured within a staple; 
         FIG. 252  is a diagram illustrating tissue captured within a staple; 
         FIG. 253  is a diagram illustrating thick tissue and a tissue thickness compensator captured within a staple; 
         FIG. 254  is a diagram illustrating thin tissue and a tissue thickness compensator captured within a staple; 
         FIG. 255  is a diagram illustrating tissue having an intermediate thickness and a tissue thickness compensator captured within a staple; 
         FIG. 256  is a diagram illustrating tissue having another intermediate thickness and a tissue thickness compensator captured within a staple; 
         FIG. 257  is a diagram illustrating thick tissue and a tissue thickness compensator captured within a staple; 
         FIG. 258  is a partial cross-sectional view of an end effector of a surgical stapling instrument illustrating a firing bar and staple-firing sled in a retracted, unfired position; 
         FIG. 259  is another partial cross-sectional view of the end effector of  FIG. 258  illustrating the firing bar and the staple-firing sled in a partially advanced position; 
         FIG. 260  is a cross-sectional view of the end effector of  FIG. 258  illustrating the firing bar in a fully advanced, or fired, position; 
         FIG. 261  is a cross-sectional view of the end effector of  FIG. 258  illustrating the firing bar in a retracted position after being fired and the staple-firing sled left in its fully fired position; 
         FIG. 262  is a detail view of the firing bar in the retracted position of  FIG. 261 ; 
         FIG. 263  is a partial cross-sectional view of an end effector of a surgical stapling instrument including a staple cartridge comprising a tissue thickness compensator and staples at least partially positioned therein; 
         FIG. 264  is another partial cross-sectional view of the end effector of  FIG. 263  illustrating the staples at least partially moved and/or rotated relative to an anvil positioned opposite the staple cartridge; 
         FIG. 265  is a partial cross-sectional view of an end effector of a surgical stapling instrument in accordance with at least one embodiment; 
         FIG. 266  is a partial cross-sectional view of an end effector in accordance with at least one alternative embodiment; 
         FIG. 267  is a partial cross-sectional view of an end effector in accordance with another alternative embodiment; 
         FIG. 268  is a perspective view of an end effector of a surgical stapling instrument in accordance with at least one embodiment; 
         FIG. 269  is a partial cross-sectional view of the end effector of  FIG. 268  illustrated in a flexed condition; 
         FIG. 270  is a partial cross-sectional view of the end effector of  FIG. 269  in a released condition; 
         FIG. 271  is a perspective view of an end effector comprising a tissue thickness compensator sock; 
         FIG. 272  is a rear perspective of the tissue thickness compensator sock in  FIG. 271 ; 
         FIG. 273  is a perspective view of an end effector comprising a plurality of rails extending from a support portion and a tissue thickness compensator having a longitudinal cavity defined therein; 
         FIG. 274  is a perspective view of the tissue thickness compensator of  FIG. 273 ; 
         FIG. 275  is a perspective view of an end effector comprising a plurality of teeth extending from a support portion and a tissue thickness compensator engaged therewith; 
         FIG. 276  is a perspective view of an anvil comprising a pocket array in accordance with at least one embodiment; 
         FIG. 277  is a partial detail view of the anvil of  FIG. 276 ; 
         FIG. 278  is a partial longitudinal cross-sectional view of the anvil of  FIG. 276 ; 
         FIG. 279  is a transverse cross-sectional view of the anvil of  FIG. 276 ; 
         FIG. 280  is an elevational view of a fired staple comprising a substantially B-shaped configuration; 
         FIG. 281  is an elevational view of a fired staple comprising one leg deformed inwardly and one leg deformed outwardly; 
         FIG. 282  is an elevational view of a fired staple comprising both legs formed outwardly; 
         FIG. 283  is a partial perspective view of a support portion of a staple cartridge comprising detachable and/or displaceable staple leg guides; 
         FIG. 284  is a partial cross-sectional view of the staple cartridge of  FIG. 283  illustrating staples being deployed from the staple cartridge; 
         FIG. 285  is a detail view of the cross-sectional view of  FIG. 284  after the staple cartridge has been fired; 
         FIG. 286  is an exploded view of a staple cartridge including a tissue thickness compensator comprising voids defined therein; 
         FIG. 287  is a diagram illustrating the tissue thickness compensator of  FIG. 286  implanted against tissue; 
         FIG. 288  is another diagram illustrating the tissue thickness compensator of  FIG. 286  implanted against tissue; 
         FIG. 289  is a cross-sectional perspective view of a staple cartridge comprising lateral retention members extending from a support portion thereof configured to hold a tissue thickness compensator in position; 
         FIG. 290  is a cross-sectional view of the staple cartridge of  FIG. 289  being utilized to staple tissue; 
         FIG. 291  is another cross-sectional view of the staple cartridge of  FIG. 289  illustrating the support portion being moved away from the implanted tissue thickness compensator; 
         FIG. 292  is a cross-sectional perspective view of a staple cartridge comprising lateral retention members configured to hold a tissue thickness compensator to a support portion; 
         FIG. 293  is a cross-sectional view of the staple cartridge of  FIG. 292  being utilized to staple tissue; 
         FIG. 294  is another cross-sectional view of the staple cartridge of  FIG. 292  illustrating the support portion being moved away from the implanted tissue thickness compensator; 
         FIG. 295  is a cross-sectional detail view of a retainer holding a tissue thickness compensator to a support portion of a staple cartridge in accordance with at least one embodiment; 
         FIG. 296  is partial cut-away view of a staple cartridge comprising staple drivers having different heights in accordance with at least one embodiment; 
         FIG. 296A  is a diagram illustrating the staple drivers of  FIG. 296  and staples having different unfired heights supported thereon; 
         FIG. 297  is a diagram illustrating a tissue thickness compensator comprising a varying thickness, staple drivers having different heights, and staples having different unformed heights; 
         FIG. 298  is a diagram illustrating the staples and the tissue thickness compensator of  FIG. 297  implanted to tissue; 
         FIG. 299  is a partial cross-sectional view of a staple cartridge comprising a tissue thickness compensator comprising a varying thickness in accordance with at least one embodiment; 
         FIG. 300  is a cross-sectional view of an end effector of a surgical stapling instrument in an open configuration; 
         FIG. 301  is cross-sectional view of the end effector of  FIG. 300  illustrated in a partially-fired configuration; 
         FIG. 302  is a cross-sectional view of the end effector of  FIG. 300  illustrated in a re-opened configuration; 
         FIG. 303  is a cross-sectional view of an end effector of a surgical stapling instrument comprising staple drivers having different heights and a contoured deck surface in accordance with at least one embodiment; 
         FIG. 304  is a cross-sectional view of an end effector of a surgical stapling instrument comprising staple drivers having different heights and a stepped deck surface in accordance with at least one embodiment; 
         FIG. 305  is a perspective view of a staple cartridge being loaded into an effector of a surgical stapling instrument utilizing a staple cartridge applicator; 
         FIG. 306  is a bottom perspective view of the staple cartridge applicator of  FIG. 305 ; 
         FIG. 307  is a side view of the staple cartridge applicator of  FIG. 305  assembled to a staple cartridge; 
         FIG. 308  is a cross-sectional view of the assembly of  FIG. 307 ; 
         FIG. 309  is a perspective view of a staple cartridge applicator assembly further including an upper tissue thickness compensator positioned on the top surface of the staple cartridge applicator in accordance with at least one embodiment; 
         FIG. 310  is an exploded view of the upper tissue thickness compensator and the staple cartridge applicator of  FIG. 309 ; 
         FIG. 310A  is an exploded view of a staple cartridge applicator assembly comprising a pull member configured to detach an upper tissue thickness compensator adhered to the staple cartridge applicator; 
         FIG. 311  is a partial exploded view of a staple cartridge applicator assembly in accordance with at least one alternative embodiment; 
         FIG. 312  is a perspective view of a staple cartridge applicator assembly comprising an upper tissue thickness compensator including a plurality of retention features extending therefrom and a staple cartridge comprising a lower tissue thickness compensator; 
         FIG. 313  is an elevational view of the staple cartridge applicator assembly of  FIG. 312  positioned within a staple cartridge channel and an anvil being closed onto the staple cartridge applicator assembly; 
         FIG. 314  is an elevational view of the anvil of  FIG. 313  in a re-opened position and the staple cartridge applicator of  FIG. 312  being removed from the end effector; 
         FIG. 314A  is a cross-sectional view of tissue positioned intermediate the upper tissue thickness compensator and the lower tissue thickness compensator of  FIG. 312 ; 
         FIG. 314B  is a cross-sectional view illustrating the upper tissue thickness compensator and the lower tissue thickness compensator stapled to the tissue and severed by a cutting member; 
         FIG. 315  is a diagram illustrating a tissue thickness compensator being inserted into an anvil in accordance with at least one embodiment; 
         FIG. 316  is a cross-sectional view of the tissue thickness compensator of  FIG. 315 ; 
         FIG. 317  is an exploded view of a tissue thickness compensator and an anvil in accordance with at least one alternative embodiment; 
         FIG. 318  is a perspective view of staple cartridge applicator assembly comprising an upper tissue thickness compensator configured to be attached to an anvil in accordance with at least one embodiment; 
         FIG. 319  is an elevational view of the staple cartridge applicator assembly of  FIG. 318  positioned within a staple cartridge channel and an anvil being moved toward the upper tissue thickness compensator; 
         FIG. 320  illustrates the staple cartridge applicator of  FIG. 318  being removed from the end effector after the upper tissue thickness compensator has been engaged with the anvil; 
         FIG. 321  is a cross-sectional end view of the anvil being moved toward the upper tissue thickness compensator of  FIG. 318 ; 
         FIG. 322  is a cross-sectional end view of the anvil engaged with the upper tissue thickness compensator; 
         FIG. 323  is a cross-sectional view of an end effector of a surgical stapling instrument comprising a staple cartridge including a segmentable tissue thickness compensator attached to a support portion of the staple cartridge by a plurality of fasteners; 
         FIG. 324  is a cross-sectional view of the end effector of  FIG. 323  illustrating a firing member in a partially-fired position; 
         FIG. 325  is a cross-sectional view of the end effector of  FIG. 323  illustrating the support portion being moved away from the partially-implanted tissue thickness compensator; 
         FIG. 326  is a partial perspective view of the support portion of  FIG. 323 ; 
         FIG. 327  is a perspective view of a staple-deploying sled in accordance with at least one embodiment; 
         FIG. 328  is an elevational view of the sled of  FIG. 327 ; 
         FIG. 329  is a perspective view of an end effector of a surgical stapling instrument comprising a staple cartridge including a tissue thickness compensator and a plurality of staple guides positioned on the tissue thickness compensator; 
         FIG. 330  is a partial cross-sectional view of the tissue thickness compensator and the staple guides of  FIG. 329  in an unfired configuration; 
         FIG. 331  is a partial cross-sectional view of the tissue thickness compensator and the staple guides of  FIG. 329  in a fired configuration; 
         FIG. 332  is a cross-sectional view of a staple cartridge comprising a tissue thickness compensator and a support portion in accordance with at least one embodiment; 
         FIG. 333  is a partial cross-sectional view of a tissue thickness compensator, a staple guide layer, and a staple in an unfired position; 
         FIG. 334  is a partial cross-sectional view of a tissue thickness compensator, a staple guide layer, and a staple in an unfired position in accordance with at least one alternative embodiment; 
         FIG. 335  is a partial cross-sectional view of a tissue thickness compensator, a staple guide layer, and a staple in an unfired position in accordance with at least one alternative embodiment; 
         FIG. 336  is a partial cross-sectional view of a tissue thickness compensator, a staple guide layer, and a staple in an unfired position in accordance with at least one alternative embodiment; 
         FIG. 337  is a partial cross-sectional view of a tissue thickness compensator, a staple guide layer, and a staple in an unfired position in accordance with at least one alternative embodiment; 
         FIG. 338  is a partial cross-sectional view of a tissue thickness compensator, a staple guide layer, and a staple in an unfired position in accordance with at least one alternative embodiment; 
         FIG. 339  is a partial cross-sectional view of a tissue thickness compensator, a staple guide layer, and a staple in an unfired position in accordance with at least one alternative embodiment; 
         FIG. 340  is a detail view of a region surrounding a tip of the staple of  FIG. 339 ; 
         FIG. 341  is a partial cross-sectional view of a tissue thickness compensator, a staple guide layer, and a staple in an unfired position in accordance with at least one alternative embodiment; 
         FIG. 342  is a detail view of a region surrounding a tip of the staple of  FIG. 341 ; 
         FIG. 343  is a partial cross-sectional view of a tissue thickness compensator, a staple guide layer, and a staple in an unfired position in accordance with at least one alternative embodiment; 
         FIG. 344  is a perspective view of a staple guide layer and a plurality of staples in an unfired position in accordance with at least one alternative embodiment; 
         FIG. 345  is an end view of a tissue thickness compensator configured to be used with a circular surgical stapler; 
         FIG. 346  is a perspective view of the tissue thickness compensator and the circular surgical stapler of  FIG. 345 ; 
         FIG. 347  is an end view of a tissue thickness compensator configured to be used with a circular surgical stapler in accordance with at least one alternative embodiment; 
         FIG. 348  is a perspective view of the tissue thickness compensator and the circular surgical stapler of  FIG. 347 ; 
         FIG. 349  is an end view of a tissue thickness compensator configured to be used with a circular surgical stapler; 
         FIG. 350  is an end view of the tissue thickness compensator of  FIG. 349  in a partially expanded configuration; 
         FIG. 351  is an elevational view of a surgical stapling instrument comprising a staple cartridge in accordance with at least one embodiment; 
         FIG. 352  is an end view of the surgical stapling instrument of  FIG. 351  positioned relative to tissue; 
         FIG. 353  is an end view of the surgical stapling instrument of  FIG. 351  further comprising a tissue thickness compensator positioned between the staple cartridge and the tissue; 
         FIG. 354  is a partial perspective view of staples deployed into tissue from the surgical stapling instrument of  FIG. 351  without a tissue thickness compensator; 
         FIG. 355  is a partial perspective view of staples deployed into tissue from the surgical stapling instrument of  FIG. 351  with a tissue thickness compensator; 
         FIG. 356  is a partial cross-sectional view of the end effector of the surgical stapling instrument of  FIG. 351  comprising an anvil plate in a first position; 
         FIG. 357  is a partial cross-sectional view of the end effector of the surgical stapling instrument of  FIG. 351  illustrating the anvil plate of  FIG. 356  in a second position; 
         FIG. 358  is a cross-sectional view of an end effector of a surgical stapling instrument comprising a staple cartridge including a gap setting element; 
         FIG. 359  is a perspective view illustrating a firing member cutting the gap setting element of  FIG. 358  at the end of firing stroke of the firing member; 
         FIG. 360  is a cross-sectional view of an end effector of a surgical stapling instrument comprising a staple cartridge including a flexible nose; 
         FIG. 361  is a cross-sectional view of the end effector of  FIG. 360  illustrating the nose in a flexed configuration; 
         FIG. 362  is a cross-sectional view of an end effector of a surgical stapling instrument comprising a staple cartridge including a slidable portion; 
         FIG. 363  is a cross-sectional view of the end effector of  FIG. 362  illustrating the slidable portion slid distally; 
         FIG. 364  is a cross-sectional view of an end effector of a surgical stapling instrument comprising a support portion comprising an inclined deck surface and a tissue thickness compensator comprising a varying thickness; 
         FIG. 365  is a cross-sectional view of an end effector of a surgical stapling instrument comprising a support portion comprising an inclined deck surface and a tissue thickness compensator comprising a uniform thickness; 
         FIG. 366  is a perspective view of a staple cartridge comprising a tissue thickness compensator having a varying thickness; 
         FIG. 367  is an end view of the staple cartridge of  FIG. 366 ; 
         FIG. 368  is a cross-sectional perspective view of a tissue thickness compensator comprising longitudinal layers; 
         FIG. 369  is a cross-sectional perspective view of a tissue thickness compensator comprising a plurality of layers in accordance with at least one alternative embodiment; 
         FIG. 370  is a perspective view of a disposable loading unit comprising retention members configured to releasably hold a tissue thickness compensator thereto; 
         FIG. 371  is a perspective view of a tissue thickness compensator including retention members configured to releasably hold the tissue thickness compensator to a disposable loading unit; 
         FIG. 372  is a perspective view of the tissue thickness compensator of  FIG. 371  attached to a disposable loading unit; 
         FIG. 373  is an end view of the disposable loading unit of  FIG. 372 ; 
         FIG. 374  is a perspective view of a tissue thickness compensator including retention members configured to releasably hold the tissue thickness compensator to a disposable loading unit; 
         FIG. 375  is a perspective view of the tissue thickness compensator of  FIG. 374  attached to a disposable loading unit; 
         FIG. 376  is an end view of the disposable loading unit of  FIG. 375 ; 
         FIG. 377  is a perspective view of a tissue thickness compensator including a retention member configured to releasably hold the tissue thickness compensator to a disposable loading unit; 
         FIG. 378  is a perspective view of the tissue thickness compensator of  FIG. 377  attached to a disposable loading unit; 
         FIG. 379  is a perspective view of a tissue thickness compensator applicator positioned within an effector of a disposable loading unit; 
         FIG. 380  is a top perspective view of the tissue thickness compensator applicator of  FIG. 379 ; 
         FIG. 381  is a bottom perspective view of the tissue thickness compensator applicator of  FIG. 379 ; 
         FIG. 382  is a perspective view of a tissue thickness compensator applicator positioned within an effector of a disposable loading unit in accordance with at least one alternative embodiment; 
         FIG. 383  is a top perspective view of the tissue thickness compensator applicator of  FIG. 382 ; 
         FIG. 384  is a bottom perspective view of the tissue thickness compensator applicator of  FIG. 382 ; 
         FIG. 385  is an elevational view of a disposable loading unit including a pivotable jaw configured to support a staple cartridge; 
         FIG. 386  is a cross-sectional view of a staple cartridge comprising a tissue thickness compensator attached to a support portion of the staple cartridge in accordance with at least one embodiment; 
         FIG. 387  is a cross-sectional view of a staple cartridge comprising a tissue thickness compensator attached to a support portion of the staple cartridge in accordance with at least one embodiment; 
         FIG. 388  is a cross-sectional view of a staple cartridge comprising a tissue thickness compensator attached to a support portion of the staple cartridge in accordance with at least one embodiment; 
         FIG. 389  is a perspective view of the tissue thickness compensator of  FIG. 387   
         FIG. 390  is a side view of an end effector of a surgical stapler including two tissue thickness compensators in accordance with at least one embodiment; 
         FIG. 391  is a cross-sectional side view of patient tissue stapled between a portion of the two tissue thickness compensators of  FIG. 390 ; 
         FIG. 392  is a perspective view of the end effector and tissue thickness compensators of  FIG. 390  illustrating an anvil of the end effector in an open position; 
         FIG. 393  is a side view of the end effector of  FIG. 390  illustrating the anvil in an open position; 
         FIG. 394  is a perspective view of the two tissue thickness compensators of  FIG. 390  connected by a hinge in accordance with at least one embodiment; 
         FIG. 395  is a side view of the two tissue thickness compensators of  FIG. 394 ; 
         FIG. 396  is a top view of the two tissue thickness compensators of  FIG. 394 ; 
         FIG. 397  is an end view of the two tissue thickness compensators of  FIG. 394 ; 
         FIG. 398  is a perspective view of a tissue thickness compensator assembly in accordance with at least one alternative embodiment; 
         FIG. 399  is a perspective view of a tissue thickness compensator assembly in accordance with at least one alternative embodiment; 
         FIG. 400  is a perspective view of a tissue thickness compensator assembly in accordance with at least one alternative embodiment; 
         FIG. 401  is a side view of a disposable loading unit including an anvil, a staple cartridge, and two tissue thickness compensators in accordance with at least one embodiment, wherein the anvil is illustrated in a closed position; 
         FIG. 402  is a side view of the disposable loading unit of  FIG. 401  illustrating the anvil in an open position; 
         FIG. 403  is a perspective view of the disposable loading unit of  FIG. 401  illustrating the anvil in an open position; 
         FIG. 404  is a side view of a disposable loading unit including an anvil, a staple cartridge, and two tissue thickness compensators in accordance with at least one alternative embodiment, wherein the anvil is illustrated in a closed position; 
         FIG. 405  is a side view of the disposable loading unit of  FIG. 404  illustrating the anvil in an open position; 
         FIG. 406  is a perspective view of the disposable loading unit of  FIG. 404  illustrating the anvil in an open position; and 
         FIG. 407  is a side view of the disposable loading unit of  FIG. 404  illustrating the anvil in an open position and with tissue positioned between a first tissue thickness compensator positioned against the staple cartridge and a second tissue thickness compensator positioned against the anvil. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate certain embodiments of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION 
     The Applicant of the present application also owns the U.S. patent applications identified below which are each herein incorporated by reference in their respective entirety: 
     U.S. patent application Ser. No. 12/894,311, entitled SURGICAL INSTRUMENTS WITH RECONFIGURABLE SHAFT SEGMENTS, now U.S. Pat. No. 8,763,877; 
     U.S. patent application Ser. No. 12/894,340, entitled SURGICAL STAPLE CARTRIDGES SUPPORTING NON-LINEARLY ARRANGED STAPLES AND SURGICAL STAPLING INSTRUMENTS WITH COMMON STAPLE-FORMING POCKETS, now U.S. Pat. No. 8,899,463; 
     U.S. patent application Ser. No. 12/894,327, entitled JAW CLOSURE ARRANGEMENTS FOR SURGICAL INSTRUMENTS, now U.S. Pat. No. 8,978,956; 
     U.S. patent application Ser. No. 12/894,351, entitled SURGICAL CUTTING AND FASTENING INSTRUMENTS WITH SEPARATE AND DISTINCT FASTENER DEPLOYMENT AND TISSUE CUTTING SYSTEMS, now U.S. Pat. No. 9,113,864; 
     U.S. patent application Ser. No. 12/894,338, entitled IMPLANTABLE FASTENER CARTRIDGE HAVING A NON-UNIFORM ARRANGEMENT, now U.S. Pat. No. 8,864,007; 
     U.S. patent application Ser. No. 12/894,369, entitled IMPLANTABLE FASTENER CARTRIDGE COMPRISING A SUPPORT RETAINER, now U.S. Patent Application Publication No. 2012/0080344; 
     U.S. patent application Ser. No. 12/894,312, entitled IMPLANTABLE FASTENER CARTRIDGE COMPRISING MULTIPLE LAYERS, now U.S. Pat. No. 8,925,782; 
     U.S. patent application Ser. No. 12/894,377, entitled SELECTIVELY ORIENTABLE IMPLANTABLE FASTENER CARTRIDGE, now U.S. Pat. No. 8,393,514; 
     U.S. patent application Ser. No. 12/894,339, entitled SURGICAL STAPLING INSTRUMENT WITH COMPACT ARTICULATION CONTROL ARRANGEMENT, now U.S. Pat. No. 8,840,003; 
     U.S. patent application Ser. No. 12/894,360, entitled SURGICAL STAPLING INSTRUMENT WITH A VARIABLE STAPLE FORMING SYSTEM, now U.S. Pat. No. 9,113,862; 
     U.S. patent application Ser. No. 12/894,322, entitled SURGICAL STAPLING INSTRUMENT WITH INTERCHANGEABLE STAPLE CARTRIDGE ARRANGEMENTS, now U.S. Pat. No. 8,740,034; 
     U.S. patent application Ser. No. 12/894,350, entitled SURGICAL STAPLE CARTRIDGES WITH DETACHABLE SUPPORT STRUCTURES AND SURGICAL STAPLING INSTRUMENTS WITH SYSTEMS FOR PREVENTING ACTUATION MOTIONS WHEN A CARTRIDGE IS NOT PRESENT, now U.S. Patent Application Publication No. 2012/0080478; 
     U.S. patent application Ser. No. 12/894,383, entitled IMPLANTABLE FASTENER CARTRIDGE COMPRISING BIOABSORBABLE LAYERS, now U.S. Pat. No. 8,752,699; 
     U.S. patent application Ser. No. 12/894,389, entitled COMPRESSIBLE FASTENER CARTRIDGE, now U.S. Pat. No. 8,740,037; 
     U.S. patent application Ser. No. 12/894,345, entitled FASTENERS SUPPORTED BY A FASTENER CARTRIDGE SUPPORT, now U.S. Pat. No. 8,783,542; 
     U.S. patent application Ser. No. 12/894,306, entitled COLLAPSIBLE FASTENER CARTRIDGE, now U.S. Pat. No. 9,044,227; 
     U.S. patent application Ser. No. 12/894,318, entitled FASTENER SYSTEM COMPRISING A PLURALITY OF CONNECTED RETENTION MATRIX ELEMENTS, now U.S. Pat. No. 8,814,024; 
     U.S. patent application Ser. No. 12/894,330, entitled FASTENER SYSTEM COMPRISING A RETENTION MATRIX AND AN ALIGNMENT MATRIX, now U.S. Pat. No. 8,757,465; 
     U.S. patent application Ser. No. 12/894,361, entitled FASTENER SYSTEM COMPRISING A RETENTION MATRIX, now U.S. Pat. No. 8,529,600; 
     U.S. patent application Ser. No. 12/894,367, entitled FASTENING INSTRUMENT FOR DEPLOYING A FASTENER SYSTEM COMPRISING A RETENTION MATRIX, now U.S. Pat. No. 9,033,203; 
     U.S. patent application Ser. No. 12/894,388, entitled FASTENER SYSTEM COMPRISING A RETENTION MATRIX AND A COVER, now U.S. Pat. No. 8,474,677; 
     U.S. patent application Ser. No. 12/894,376, entitled FASTENER SYSTEM COMPRISING A PLURALITY OF FASTENER CARTRIDGES, now U.S. Pat. No. 9,044,228; 
     U.S. patent application Ser. No. 13/097,865, entitled SURGICAL STAPLER ANVIL COMPRISING A PLURALITY OF FORMING POCKETS, now U.S. Patent Application Publication No. 2012/0080488; 
     U.S. patent application Ser. No. 13/097,936, entitled TISSUE THICKNESS COMPENSATOR FOR A SURGICAL STAPLER, now U.S. Pat. No. 8,657,176; 
     U.S. patent application Ser. No. 13/097,954, entitled STAPLE CARTRIDGE COMPRISING A VARIABLE THICKNESS COMPRESSIBLE PORTION, now U.S. Patent Application Publication No. 2012/0080340; 
     U.S. patent application Ser. No. 13/097,856, entitled STAPLE CARTRIDGE COMPRISING STAPLES POSITIONED WITHIN A COMPRESSIBLE PORTION THEREOF, now U.S. Patent Application Publication No. 2012/0080336; 
     U.S. patent application Ser. No. 13/097,928, entitled TISSUE THICKNESS COMPENSATOR COMPRISING DETACHABLE PORTIONS, now U.S. Pat. No. 8,746,535; 
     U.S. patent application Ser. No. 13/097,891, entitled TISSUE THICKNESS COMPENSATOR FOR A SURGICAL STAPLER COMPRISING AN ADJUSTABLE ANVIL, now U.S. Pat. No. 8,864,009; 
     U.S. patent application Ser. No. 13/097,948, entitled STAPLE CARTRIDGE COMPRISING AN ADJUSTABLE DISTAL PORTION, now U.S. Pat. No. 8,978,954; 
     U.S. patent application Ser. No. 13/097,907, entitled COMPRESSIBLE STAPLE CARTRIDGE ASSEMBLY, now U.S. Patent Application Publication No. 2012/0080338; 
     U.S. patent application Ser. No. 13/097,861, entitled TISSUE THICKNESS COMPENSATOR COMPRISING PORTIONS HAVING DIFFERENT PROPERTIES, now U.S. Pat. No. 9,113,865; 
     U.S. patent application Ser. No. 13/097,869, entitled STAPLE CARTRIDGE LOADING ASSEMBLY, now U.S. Pat. No. 8,857,694; 
     U.S. patent application Ser. No. 13/097,917, entitled COMPRESSIBLE STAPLE CARTRIDGE COMPRISING ALIGNMENT MEMBERS, now U.S. Pat. No. 8,777,004; 
     U.S. patent application Ser. No. 13/097,873, entitled STAPLE CARTRIDGE COMPRISING A RELEASABLE PORTION, now U.S. Pat. No. 8,740,038; 
     U.S. patent application Ser. No. 13/097,938, entitled STAPLE CARTRIDGE COMPRISING COMPRESSIBLE DISTORTION RESISTANT COMPONENTS, now U.S. Pat. No. 9,016,542; 
     U.S. patent application Ser. No. 13/097,924, entitled STAPLE CARTRIDGE COMPRISING A TISSUE THICKNESS COMPENSATOR, now U.S. Pat. No. 9,168,038; 
     U.S. patent application Ser. No. 13/242,029, entitled SURGICAL STAPLER WITH FLOATING ANVIL, now U.S. Pat. No. 8,893,949; 
     U.S. patent application Ser. No. 13/242,066, entitled CURVED END EFFECTOR FOR A STAPLING INSTRUMENT, now U.S. Patent Application Publication No. 2012/0080498; 
     U.S. patent application Ser. No. 13/242,086, entitled STAPLE CARTRIDGE INCLUDING COLLAPSIBLE DECK, now U.S. Pat. No. 9,055,941; 
     U.S. patent application Ser. No. 13/241,912, entitled STAPLE CARTRIDGE INCLUDING COLLAPSIBLE DECK ARRANGEMENT, now U.S. Pat. No. 9,050,084; 
     U.S. patent application Ser. No. 13/241,922, entitled SURGICAL STAPLER WITH STATIONARY STAPLE DRIVERS, now U.S. Pat. No. 9,216,019; 
     U.S. patent application Ser. No. 13/241,637, entitled SURGICAL INSTRUMENT WITH TRIGGER ASSEMBLY FOR GENERATING MULTIPLE ACTUATION MOTIONS, now U.S. Pat. No. 8,789,741; and 
     U.S. patent application Ser. No. 13/241,629, entitled SURGICAL INSTRUMENT WITH SELECTIVELY ARTICULATABLE END EFFECTOR, now U.S. Patent Application Publication No. 2012/0074200. 
     The Applicant of the present application also owns the U.S. patent applications identified below which were filed on even date herewith and which are each herein incorporated by reference in their respective entirety: 
     U.S. application Ser. No. 13/433,096, entitled TISSUE THICKNESS COMPENSATOR COMPRISING A PLURALITY OF CAPSULES, now U.S. Patent Application Publication No. 2012/0241496; 
     U.S. application Ser. No. 13/433,103, entitled TISSUE THICKNESS COMPENSATOR COMPRISING A PLURALITY OF LAYERS, now U.S. Patent Application Publication No. 2012/0241498; 
     U.S. application Ser. No. 13/433,098, entitled EXPANDABLE TISSUE THICKNESS COMPENSATOR, now U.S. Patent Application Publication No. 2012/0241491. 
     U.S. application Ser. No. 13/433,102, entitled TISSUE THICKNESS COMPENSATOR COMPRISING A RESERVOIR, now U.S. Patent Application Publication No. 2012/0241497; 
     U.S. application Ser. No. 13/433,114, entitled RETAINER ASSEMBLY INCLUDING A TISSUE THICKNESS COMPENSATOR, now U.S. Patent Application Publication No. 2012/0241499; 
     U.S. application Ser. No. 13/433,136, entitled TISSUE THICKNESS COMPENSATOR COMPRISING AT LEAST ONE MEDICAMENT, now U.S. Patent Application Publication No. 2012/0241492; 
     U.S. application Ser. No. 13/433,141, entitled TISSUE THICKNESS COMPENSATOR COMPRISING CONTROLLED RELEASE AND EXPANSION, now U.S. Patent Application Publication No. 2012/0241493; 
     U.S. application Ser. No. 13/433,144, entitled TISSUE THICKNESS COMPENSATOR COMPRISING FIBERS TO PRODUCE A RESILIENT LOAD, now U.S. Patent Application Publication No. 2012/0241500; 
     U.S. application Ser. No. 13/433,148, entitled TISSUE THICKNESS COMPENSATOR COMPRISING STRUCTURE TO PRODUCE A RESILIENT LOAD, now U.S. Patent No. 2012/0241501; 
     U.S. application Ser. No. 13/433,155, entitled TISSUE THICKNESS COMPENSATOR COMPRISING RESILIENT MEMBERS, now U.S. Patent Application Publication No. 2012/0241502; 
     U.S. application Ser. No. 13/433,163, entitled METHODS FOR FORMING TISSUE THICKNESS COMPENSATOR ARRANGEMENTS FOR SURGICAL STAPLERS, now U.S. Patent Application Publication No. 2012/0248169; 
     U.S. application Ser. No. 13/433,175, entitled LAYERED TISSUE THICKNESS COMPENSATOR, now U.S. Patent Application Publication No. 2012/0253298; 
     U.S. application Ser. No. 13/433,179, entitled TISSUE THICKNESS COMPENSATORS FOR CIRCULAR SURGICAL STAPLERS, now U.S. Patent Application Publication No. 2012/0241505; 
     U.S. application Ser. No. 13/433,115, entitled TISSUE THICKNESS COMPENSATOR COMPRISING CAPSULES DEFINING A LOW PRESSURE ENVIRONMENT, now U.S. Pat. No. 9,204,880; 
     U.S. application Ser. No. 13/433,118, entitled TISSUE THICKNESS COMPENSATOR COMPRISED OF A PLURALITY OF MATERIALS, now U.S. Patent Application Publication No. 2013/0256365; 
     U.S. application Ser. No. 13/433,135, entitled MOVABLE MEMBER FOR USE WITH A TISSUE THICKNESS COMPENSATOR, now U.S. Patent Application Publication No. 2013/0256382; 
     U.S. application Ser. No. 13/433,129, entitled TISSUE THICKNESS COMPENSATOR COMPRISING A PLURALITY OF MEDICAMENTS, now U.S. Pat. No. 9,211,120; 
     U.S. application Ser. No. 13/433,140, entitled TISSUE THICKNESS COMPENSATOR AND METHOD FOR MAKING THE SAME, now U.S. Patent Application Publication No. 2013/0256368; 
     U.S. application Ser. No. 13/433,147, entitled TISSUE THICKNESS COMPENSATOR COMPRISING CHANNELS, now U.S. Patent Application Publication No. 2013/0256369; 
     U.S. application Ser. No. 13/433,126, entitled TISSUE THICKNESS COMPENSATOR COMPRISING TISSUE INGROWTH FEATURES, now U.S. Patent Application Publication No. 2013/0256366; and 
     U.S. application Ser. No. 13/433,132, entitled DEVICES AND METHODS FOR ATTACHING TISSUE THICKNESS COMPENSATING MATERIALS TO SURGICAL STAPLING INSTRUMENTS, now U.S. Patent Application Publication No. 2013/0256373. 
     Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those of ordinary skill in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the various embodiments of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention. 
     Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” or “an embodiment”, or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment”, or “in an embodiment”, or the like, in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Thus, the particular features, structures, or characteristics illustrated or described in connection with one embodiment may be combined, in whole or in part, with the features structures, or characteristics of one or more other embodiments without limitation. Such modifications and variations are intended to be included within the scope of the present invention. 
     The terms “proximal” and “distal” are used herein with reference to a clinician manipulating the handle portion of the surgical instrument. The term “proximal” referring to the portion closest to the clinician and the term “distal” referring to the portion located away from the clinician. It will be further appreciated that, for convenience and clarity, spatial terms such as “vertical”, “horizontal”, “up”, and “down” may be used herein with respect to the drawings. However, surgical instruments are used in many orientations and positions, and these terms are not intended to be limiting and/or absolute. 
     Various exemplary devices and methods are provided for performing laparoscopic and minimally invasive surgical procedures. However, the person of ordinary skill in the art will readily appreciate that the various methods and devices disclosed herein can be used in numerous surgical procedures and applications including, for example, in connection with open surgical procedures. As the present Detailed Description proceeds, those of ordinary skill in the art will further appreciate that the various instruments disclosed herein can be inserted into a body in any way, such as through a natural orifice, through an incision or puncture hole formed in tissue, etc. The working portions or end effector portions of the instruments can be inserted directly into a patient&#39;s body or can be inserted through an access device that has a working channel through which the end effector and elongated shaft of a surgical instrument can be advanced. 
     Turning to the Drawings wherein like numerals denote like components throughout the several views,  FIG. 1  depicts a surgical instrument  10  that is capable of practicing several unique benefits. The surgical stapling instrument  10  is designed to manipulate and/or actuate various forms and sizes of end effectors  12  that are operably attached thereto. In the embodiment depicted in  FIGS. 1-1E , for example, the end effector  12  includes an elongated channel  14  that forms a lower jaw  13  of the end effector  12 . The elongated channel  14  is configured to support an “implantable” staple cartridge  30  and also movably support an anvil  20  that functions as an upper jaw  15  of the end effector  12 . 
     In various embodiments, the elongated channel  14  may be fabricated from, for example, 300 &amp; 400 Series, 17-4 &amp; 17-7 stainless steel, titanium, etc. and be formed with spaced side walls  16 . The anvil  20  may be fabricated from, for example, 300 &amp; 400 Series, 17-4 &amp; 17-7 stainless steel, titanium, etc. and have a staple forming undersurface, generally labeled as  22  that has a plurality of staple forming pockets  23  formed therein. See  FIGS. 1B-1E . In addition, the anvil  20  has a bifurcated ramp assembly  24  that protrudes proximally therefrom. An anvil pin  26  protrudes from each lateral side of the ramp assembly  24  to be received within a corresponding slot or opening  18  in the side walls  16  of the elongated channel  14  to facilitate its movable or pivotable attachment thereto. 
     Various forms of implantable staple cartridges may be employed with the various embodiments of the surgical instruments disclosed herein. Specific staple cartridge configurations and constructions will be discussed in further detail below. However, in the embodiment depicted in  FIG. 1A , an implantable staple cartridge  30  is shown. In at least one embodiment, the staple cartridge  30  has a body portion  31  that consists of a compressible hemostat material such as, for example, oxidized regenerated cellulose (“ORC”) or a bio-absorbable foam in which lines of unformed metal staples  32  are supported. In at least some embodiments, in order to prevent the staple from being affected and the hemostat material from being activated during the introduction and positioning process, the entire cartridge may be coated or wrapped in a biodegradable film  38  such as a polydioxanon film sold under the trademark PDS® or with a Polyglycerol sebacate (PGS) film or other biodegradable films formed from PGA (Polyglycolic acid, marketed under the trade mark Vicryl), PCL (Polycaprolactone), PLA or PLLA (Polylactic acid), PHA (polyhydroxyalkanoate), PGCL (poliglecaprone 25, sold under the trademark Monocryl) or a composite of PGA, PCL, PLA, PDS that would be impermeable until ruptured. The body  31  of staple cartridge  30  is sized to be removably supported within the elongated channel  14  as shown such that each staple  32  therein is aligned with corresponding staple forming pockets  23  in the anvil when the anvil  20  is driven into forming contact with the staple cartridge  30 . 
     In use, once the end effector  12  has been positioned adjacent the target tissue, the end effector  12  is manipulated to capture or clamp the target tissue between an upper face  36  of the staple cartridge  30  and the staple forming surface  22  of the anvil  20 . The staples  32  are formed by moving the anvil  20  in a path that is substantially parallel to the elongated channel  14  to bring the staple forming surface  22  and, more particularly, the staple forming pockets  23  therein into substantially simultaneous contact with the upper face  36  of the staple cartridge  30 . As the anvil  20  continues to move into the staple cartridge  30 , the legs  34  of the staples  32  contact a corresponding staple forming pocket  23  in anvil  20  which serves to bend the staple legs  34  over to form the staples  32  into a “B shape”. Further movement of the anvil  20  toward the elongated channel  14  will further compress and form the staples  32  to a desired final formed height “FF”. 
     The above-described staple forming process is generally depicted in  FIGS. 1B-1E . For example,  FIG. 1B  illustrates the end effector  12  with target tissue “T” between the anvil  20  and the upper face  36  of the implantable staple cartridge  30 .  FIG. 1C  illustrates the initial clamping position of the anvil  20  wherein the anvil has 20 been closed onto the target tissue “T” to clamp the target tissue “T” between the anvil  20  and the upper face  36  of the staple cartridge  30 .  FIG. 1D  illustrates the initial staple formation wherein the anvil  20  has started to compress the staple cartridge  30  such that the legs  34  of the staples  32  are starting to be formed by the staple forming pockets  23  in the anvil  20 .  FIG. 1E  illustrates the staple  32  in its final formed condition through the target tissue “T” with the anvil  20  removed for clarity purposes. Once the staples  32  have been formed and fastened to the target tissue “T”, the surgeon will move the anvil  20  to the open position to enable the cartridge body  31  and the staples  32  to remain affixed to the target tissue while the end effector  12  is being withdrawn from the patient. The end effector  12  forms all of the staples simultaneously as the two jaws  13 ,  15  are clamped together. The remaining “crushed” body materials  31  act as both a hemostat (the ORC) and a staple line reinforcement (PGA, PDS or any of the other film compositions mentioned above 38). Also, since the staples  32  never have to leave the cartridge body  31  during forming, the likelihood of the staples  32  being malformed during forming is minimized. As used herein the term “implantable” means that, in addition to the staples, the cartridge body materials that support the staples will also remain in the patient and may eventually be absorbed by the patient&#39;s body. Such implantable staple cartridges are distinguishable from prior cartridge arrangements that remain positioned within the end effector in their entirety after they have been fired. 
     In various implementations, the end effector  12  is configured to be coupled to an elongated shaft assembly  40  that protrudes from a handle assembly  100 . The end effector  12  (when closed) and the elongated shaft assembly  40  may have similar cross-sectional shapes and be sized to operably pass through a trocar tube or working channel in another form of access instrument. As used herein, the term “operably pass” means that the end effector and at least a portion of the elongated shaft assembly may be inserted through or passed through the channel or tube opening and can be manipulated therein as needed to complete the surgical stapling procedure. In some embodiments, when in a closed position, the jaws  13  and  15  of the end effector  12  may provide the end effector with a roughly circular cross-sectional shape that facilitates its passage through a circular passage/opening. However, the end effectors of various embodiments of the present invention, as well as the elongated shaft assembly embodiments, could conceivably be provided with other cross-sectional shapes that could otherwise pass through access passages and openings that have non-circular cross-sectional shapes. Thus, an overall size of a cross-section of a closed end effector will be related to the size of the passage or opening through which it is intended to pass. Thus, one end effector for example, may be referred to as a “5 mm” end effector which means it can operably pass through an opening that is at least approximately 5 mm in diameter. 
     In various embodiments, the elongated shaft assembly  40  may have an outer diameter that is substantially the same as the outer diameter of the end effector  12  when in a closed position. For example, a 5 mm end effector may be coupled to an elongated shaft assembly  40  that has 5 mm cross-sectional diameter. However, as the present Detailed Description proceeds, it will become apparent that various embodiments of the present may be effectively used in connection with different sizes of end effectors. For example, a 10 mm end effector may be attached to an elongated shaft that has a 5 mm cross-sectional diameter. Conversely, for those applications wherein a 10 mm or larger access opening or passage is provided, the elongated shaft assembly  40  may have a 10 mm (or larger) cross-sectional diameter, but may also be able to actuate a 5 mm or 10 mm end effector. Accordingly, the outer shaft  40  may have an outer diameter that is the same as or is different from the outer diameter of a closed end effector  12  attached thereto. 
     As depicted, the elongated shaft assembly  40  extends distally from the handle assembly  100  in a generally straight line to define a longitudinal axis A-A. In various embodiments, for example, the elongated shaft assembly  40  may be approximately 9-16 inches (229-406 mm) long. However, the elongated shaft assembly  40  may be provided in other lengths and, in other embodiments, may have joints therein or be otherwise configured to facilitate articulation of the end effector  12  relative to other portions of the shaft or handle assembly as will be discussed in further detail below. In various embodiments, the elongated shaft assembly  40  includes a spine member  50  that extends from the handle assembly  100  to the end effector  12 . The proximal end of the elongated channel  14  of the end effector  12  has a pair of retention trunnions  17  protruding therefrom that are sized to be received within corresponding trunnion openings or cradles  52  that are provided in a distal end of the spine member  50  to enable the end effector  12  to be removably coupled the elongated shaft assembly  40 . The spine member  50  may be fabricated from, for example, 6061 or 7075 aluminum, stainless steel, titanium, etc. 
     In various embodiments, the handle assembly  100  comprises a pistol grip-type housing that may be fabricated in two or more pieces for assembly purposes. For example, the handle assembly  100  as shown comprises a right hand case member  102  and a left hand case member (not illustrated) that are molded or otherwise fabricated from a polymer or plastic material and are designed to mate together. Such case members may be attached together by snap features, pegs and sockets molded or otherwise formed therein and/or by adhesive, screws, etc. The spine member  50  has a proximal end  54  that has a flange  56  formed thereon. The flange  56  is configured to be rotatably supported within a groove  106  formed by mating ribs  108  that protrude inwardly from each of the case members  102 ,  104 . Such arrangement facilitates the attachment of the spine member  50  to the handle assembly  100  while enabling the spine member  50  to be rotated relative to the handle assembly  100  about the longitudinal axis A-A in a 360° path. 
     As can be further seen in  FIG. 1 , the spine member  50  passes through and is supported by a mounting bushing  60  that is rotatably affixed to the handle assembly  100 . The mounting bushing  60  has a proximal flange  62  and a distal flange  64  that define a rotational groove  65  that is configured to rotatably receive a nose portion  101  of the handle assembly  100  therebetween. Such arrangement enables the mounting bushing  60  to rotate about longitudinal axis A-A relative to the handle assembly  100 . The spine member  50  is non-rotatably pinned to the mounting bushing  60  by a spine pin  66 . In addition, a rotation knob  70  is attached to the mounting bushing  60 . In one embodiment, for example, the rotation knob  70  has a hollow mounting flange portion  72  that is sized to receive a portion of the mounting bushing  60  therein. In various embodiments, the rotation knob  70  may be fabricated from, for example, glass or carbon filled Nylon, polycarbonate, Ultem®, etc. and is affixed to the mounting bushing  60  by the spine pin  66  as well. In addition, an inwardly protruding retention flange  74  is formed on the mounting flange portion  72  and is configured to extend into a radial groove  68  formed in the mounting bushing  60 . Thus, the surgeon may rotate the spine member  50  (and the end effector  12  attached thereto) about longitudinal axis A-A in a 360° path by grasping the rotation knob  70  and rotating it relative to the handle assembly  100 . 
     In various embodiments, the anvil  20  is retained in an open position by an anvil spring  21  and/or another biasing arrangement. The anvil  20  is selectively movable from the open position to various closed or clamping and firing positions by a firing system, generally designated as  109 . The firing system  109  includes a “firing member”  110  which, in various embodiments, comprises a hollow firing tube  110 . The hollow firing tube  110  is axially movable on the spine member  50  and thus forms the outer portion of the elongated shaft assembly  40 . The firing tube  110  may be fabricated from a polymer or other suitable material and have a proximal end that is attached to a firing yoke  114  of the firing system  109 . In various embodiments for example, the firing yoke  114  may be over-molded to the proximal end of the firing tube  110 . However, other fastener arrangements may be employed. 
     As can be seen in  FIG. 1 , the firing yoke  114  may be rotatably supported within a support collar  120  that is configured to move axially within the handle assembly  100 . In various embodiments, the support collar  120  has a pair of laterally extending fins that are sized to be slidably received within fin slots formed in the right and left hand case members. Thus, the support collar  120  may slide axially within the handle housing  100  while enabling the firing yoke  114  and firing tube  110  to rotate relative thereto about the longitudinal axis A-A. In various embodiments, a longitudinal slot is provided through the firing tube  110  to enable the spine pin  66  to extend therethrough into the spine member  50  while facilitating the axial travel of the firing tube  110  on the spine member  50 . 
     The firing system  109  further comprises a firing trigger  130  which serves to control the axial travel of the firing tube  110  on the spine member  50 . See  FIG. 1 . Such axial movement in the distal direction of the firing tube  110  into firing interaction with the anvil  20  is referred to herein as “firing motion”. As can be seen in  FIG. 1 , the firing trigger  130  is movably or pivotally coupled to the handle assembly  100  by a pivot pin  132 . A torsion spring  135  is employed to bias the firing trigger  130  away from the pistol grip portion  107  of the handle assembly  100  to an un-actuated “open” or starting position. As can be seen in  FIG. 1 , the firing trigger  130  has an upper portion  134  that is movably attached to (pinned) firing links  136  that are movably attached to (pinned) the support collar  120 . Thus, movement of the firing trigger  130  from the starting position ( FIG. 1 ) toward an ending position adjacent the pistol grip portion  107  of the handle assembly  100  will cause the firing yoke  114  and the firing tube  110  to move in the distal direction “DD”. Movement of the firing trigger  130  away from the pistol grip portion  107  of the handle assembly  100  (under the bias of the torsion spring  135 ) will cause the firing yoke  114  and firing tube  110  to move in the proximal direction “PD” on the spine member  50 . 
     Various embodiments of the present invention may be employed with different sizes and configurations of implantable staple cartridges. For example, the surgical instrument  10 , when used in connection with a first firing adapter  140 , may be used with a 5 mm end effector  12  that is approximately 20 mm long (or in other lengths) which supports an implantable staple cartridge  30 . Such end effector size may be particularly well-suited, for example, to complete relatively fine dissection and vascular transactions. However, as will be discussed in further detail below, the surgical instrument  10  may also be employed, for example, in connection with other sizes of end effectors and staple cartridges by replacing the first firing adapter  140  with a second firing adapter. In still other embodiments, the elongated shaft assembly  40  may configured to be attached to only one form or size of end effector. 
     One method of removably coupling the end effector  12  to the spine member  50  will now be explained. The coupling process is commenced by inserting the retention trunnions  17  on the elongated channel  14  into the trunnion cradles  52  in the spine member  50 . Thereafter, the surgeon advances the firing trigger  130  toward the pistol grip  107  of the housing assembly  100  to distally advance the firing tube  110  and the first firing adapter  140  over a proximal end portion  47  of the elongated channel  14  to thereby retain the trunnions  17  in their respective cradles  52 . Such position of the first firing adapter  140  over the trunnions  17  is referred to herein as the “coupled position”. Various embodiments of the present invention may also have an end effector locking assembly for locking the firing trigger  130  in position after an end effector  12  has been attached to the spine member  50 . 
     More specifically, one embodiment of the end effector locking assembly  160  includes a retention pin  162  that is movably supported in the upper portion  134  of the firing trigger  130 . As discussed above, the firing tube  110  must initially be advanced distally to the coupled position wherein the first firing adapter  140  retains the retention trunnions  17  of the end effector  12  in the trunnion cradles  52  in the spine member  50 . The surgeon advances the firing adapter  140  distally to the coupled position by pulling the firing trigger  130  from the starting position toward the pistol grip  107 . As the firing trigger  130  is initially actuated, the retention pin  162  is moved distally until the firing tube  110  has advanced the first firing adapter  140  to the coupled position at which point the retention pin  162  is biased into a locking cavity  164  formed in the case member. In various embodiments, when the retention pin  162  enters into the locking cavity  164 , the pin  162  may make an audible “click” or other sound, as well as provide a tactile indication to the surgeon that the end effector  12  has been “locked” onto the spine member  50 . In addition, the surgeon cannot inadvertently continue to actuate the firing trigger  130  to start to form staples  32  in the end effector  12  without intentionally biasing the retention pin  162  out of the locking cavity  164 . Similarly, if the surgeon releases the firing trigger  130  when in the coupled position, it is retained in that position by the retention pin  162  to prevent the firing trigger  130  from returning to the starting position and thereby releasing the end effector  12  from the spine member  50 . 
     Various embodiments of the present invention may further include a firing system lock button  137  that is pivotally attached to the handle assembly  100 . In one form, the firing system lock button  137  has a latch  138  formed on a distal end thereof that is oriented to engage the firing yoke  114  when the firing release button is in a first latching position. As can be seen in  FIG. 1 , a latch spring  139  serves to bias the firing system lock button  137  to the first latching position. In various circumstances, the latch  138  serves to engage the firing yoke  114  at a point where the position of the firing yoke  114  on the spine member  50  corresponds to a point wherein the first firing adapter  140  is about to distally advance up the clamping ramp  28  on the anvil  20 . It will be understood that, as the first firing adapter  140  advances axially up the clamping ramp  28 , the anvil  20  will move in a path such that its staple forming surface portion  22  is substantially parallel to the upper face  36  of the staple cartridge  30 . 
     After the end effector  12  has been coupled to the spine member  50 , the staple forming process is commenced by first depressing the firing system lock button  137  to enable the firing yoke  114  to be further moved distally on the spine member  50  and ultimately compress the anvil  20  into the staple cartridge  30 . After depressing the firing system lock button  137 , the surgeon continues to actuate the firing trigger  130  towards the pistol grip  107  thereby driving the first staple collar  140  up the corresponding staple forming ramp  29  to force the anvil  20  into forming contact with the staples  32  in the staple cartridge  30 . The firing system lock button  137  prevents the inadvertent forming of the staples  32  until the surgeon is ready to start that process. In this embodiment, the surgeon must depress the firing system lock button  137  before the firing trigger  130  may be further actuated to begin the staple forming process. 
     The surgical instrument  10  may be solely used as a tissue stapling device if so desired. However, various embodiments of the present invention may also include a tissue cutting system, generally designated as  170 . In at least one form, the tissue cutting system  170  comprises a knife member  172  that may be selectively advanced from an un-actuated position adjacent the proximal end of the end effector  12  to an actuated position by actuating a knife advancement trigger  200 . The knife member  172  is movably supported within the spine member  50  and is attached or otherwise protrudes from a knife rod  180 . The knife member  172  may be fabricated from, for example, 420 or 440 stainless steel with a hardness of greater than 38HRC (Rockwell Hardness C-scale) and have a tissue cutting edge  176  formed on the distal end  174  thereof and be configured to slidably extend through a slot in the anvil  20  and a centrally disposed slot  33  in the staple cartridge  30  to cut through tissue that is clamped in the end effector  12 . In various embodiments, the knife rod  180  extends through the spine member  50  and has a proximal end portion which drivingly interfaces with a knife transmission that is operably attached to the knife advance trigger  200 . In various embodiments, the knife advance trigger  200  is attached to pivot pin  132  such that it may be pivoted or otherwise actuated without actuating the firing trigger  130 . In various embodiments, a first knife gear  192  is also attached to the pivot pin  132  such that actuation of the knife advance trigger  200  also pivots the first knife gear  192 . A firing return spring  202  is attached between the first knife gear  192  and the handle housing  100  to bias the knife advancement trigger  200  to a starting or un-actuated position. 
     Various embodiments of the knife transmission also include a second knife gear  194  that is rotatably supported on a second gear spindle and in meshing engagement with the first knife gear  192 . The second knife gear  194  is in meshing engagement with a third knife gear  196  that is supported on a third gear spindle. Also supported on the third gear spindle  195  is a fourth knife gear  198 . The fourth knife gear  198  is adapted to drivingly engage a series of annular gear teeth or rings on a proximal end of the knife rod  180 . Thus, such arrangement enables the fourth knife gear  198  to axially drive the knife rod  180  in the distal direction “DD” or proximal direction “PD” while enabling the firing rod  180  to rotate about longitudinal axis A-A with respect to the fourth knife gear  198 . Accordingly, the surgeon may axially advance the firing rod  180  and ultimately the knife member  172  distally by pulling the knife advancement trigger  200  towards the pistol grip  107  of the handle assembly  100 . 
     Various embodiments of the present invention further include a knife lockout system  210  that prevents the advancement of the knife member  172  unless the firing trigger  130  has been pulled to the fully fired position. Such feature will therefore prevent the activation of the knife advancement system  170  unless the staples have first been fired or formed into the tissue. As can be seen in  FIG. 1 , various implementations of the knife lockout system  210  comprise a knife lockout bar  211  that is pivotally supported within the pistol grip portion  107  of the handle assembly  100 . The knife lockout bar  211  has an activation end  212  that is adapted to be engaged by the firing trigger  130  when the firing trigger  130  is in the fully fired position. In addition, the knife lockout bar  211  has a retaining hook  214  on its other end that is adapted to hookingly engage a latch rod  216  on the first cut gear  192 . A knife lock spring  218  is employed to bias the knife lockout bar  211  to a “locked” position wherein the retaining hook  214  is retained in engagement with the latch rod  216  to thereby prevent actuation of the knife advancement trigger  200  unless the firing trigger  130  is in the fully fired position. 
     After the staples have been “fired” (formed) into the target tissue, the surgeon may depress the firing trigger release button  167  to enable the firing trigger  130  to return to the starting position under the bias of the torsion spring  135  which enables the anvil  20  to be biased to an open position under the bias of spring  21 . When in the open position, the surgeon may withdraw the end effector  12  leaving the implantable staple cartridge  30  and staples  32  behind. In applications wherein the end effector was inserted through a passage, working channel, etc. the surgeon will return the anvil  20  to the closed position by activating the firing trigger  130  to enable the end effector  12  to be withdrawn out through the passage or working channel. If, however, the surgeon desires to cut the target tissue after firing the staples, the surgeon activates the knife advancement trigger  200  in the above-described manner to drive the knife bar  172  through the target tissue to the end of the end effector. Thereafter, the surgeon may release the knife advancement trigger  200  to enable the firing return spring  202  to cause the firing transmission to return the knife bar  172  to the starting (un-actuated) position. Once the knife bar  172  has been returned to the starting position, the surgeon may open the end effector jaws  13 ,  15  to release the implantable cartridge  30  within the patient and then withdraw the end effector  12  from the patient. Thus, such surgical instruments facilitate the use of small implantable staple cartridges that may be inserted through relatively smaller working channels and passages, while providing the surgeon with the option to fire the staples without cutting tissue or if desired to also cut tissue after the staples have been fired. 
     Various unique and novel embodiments of the present invention employ a compressible staple cartridge that supports staples in a substantially stationary position for forming contact by the anvil. In various embodiments, the anvil is driven into the unformed staples wherein, in at least one such embodiment, the degree of staple formation attained is dependent upon how far the anvil is driven into the staples. Such an arrangement provides the surgeon with the ability to adjust the amount of forming or firing pressure applied to the staples and thereby alter the final formed height of the staples. In other various embodiments of the present invention, surgical stapling arrangements can employ staple driving elements which can lift the staples toward the anvil. Such embodiments are described in greater detail further below. 
     In various embodiments, with regard to the embodiments described in detail above, the amount of firing motion that is applied to the movable anvil is dependent upon the degree of actuation of the firing trigger. For example, if the surgeon desires to attain only partially formed staples, then the firing trigger is only partially depressed inward towards the pistol grip  107 . To attain more staple formation, the surgeon simply compresses the firing trigger further which results in the anvil being further driven into forming contact with the staples. As used herein, the term “forming contact” means that the staple forming surface or staple forming pockets have contacted the ends of the staple legs and have started to form or bend the legs over into a formed position. The degree of staple formation refers to how far the staple legs have been folded over and ultimately relates to the forming height of the staple as referenced above. Those of ordinary skill in the art will further understand that, because the anvil  20  moves in a substantially parallel relationship with respect to the staple cartridge as the firing motions are applied thereto, the staples are formed substantially simultaneously with substantially the same formed heights. 
       FIGS. 2 and 3  illustrate an alternative end effector  12 ″ that is similar to the end effector  12 ′ described above, except with the following differences that are configured to accommodate a knife bar  172 ′. The knife bar  172 ′ is coupled to or protrudes from a knife rod  180  and is otherwise operated in the above described manner with respect to the knife bar  172 . However, in this embodiment, the knife bar  172 ′ is long enough to traverse the entire length of the end effector  12 ″ and therefore, a separate distal knife member is not employed in the end effector  12 ″. The knife bar  172 ′ has an upper transverse member  173 ′ and a lower transverse member  175 ′ formed thereon. The upper transverse member  173 ′ is oriented to slidably transverse a corresponding elongated slot  250  in anvil  20 ″ and the lower transverse member  175 ′ is oriented to traverse an elongated slot  252  in the elongated channel  14 ″ of the end effector  12 ″. A disengagement slot (not shown) is also provided in the anvil  20 ″ such that when the knife bar  172 ′ has been driven to an ending position within end effector  12 ″, the upper transverse member  173 ′ drops through the corresponding slot to enable the anvil  20 ″ to move to the open position to disengage the stapled and cut tissue. The anvil  20 ″ may be otherwise identical to anvil  20  described above and the elongated channel  14 ″ may be otherwise identical to elongated channel  14  described above. 
     In these embodiments, the anvil  20 ″ is biased to a fully open position ( FIG. 2 ) by a spring or other opening arrangement (not shown). The anvil  20 ″ is moved between the open and fully clamped positions by the axial travel of the firing adapter  150  in the manner described above. Once the firing adapter  150  has been advanced to the fully clamped position ( FIG. 3 ), the surgeon may then advance the knife bar  172 ″ distally in the manner described above. If the surgeon desires to use the end effector as a grasping device to manipulate tissue, the firing adapter may be moved proximally to allow the anvil  20 ″ to move away from the elongated channel  14 ″ as represented in  FIG. 4  in broken lines. In this embodiment, as the knife bar  172 ″ moves distally, the upper transverse member  173 ′ and the lower transverse member  175 ′ draw the anvil  20 ″ and elongated channel  14 ″ together to achieve the desired staple formation as the knife bar  172 ″ is advanced distally through the end effector  12 ″. See  FIG. 5 . Thus, in this embodiment, staple formation occurs simultaneously with tissue cutting, but the staples themselves may be sequentially formed as the knife bar  172 ″ is driven distally. 
     The unique and novel features of the various surgical staple cartridges and the surgical instruments of the present invention enable the staples in those cartridges to be arranged in one or more linear or non-linear lines. A plurality of such staple lines may be provided on each side of an elongated slot that is centrally disposed within the staple cartridge for receiving the tissue cutting member therethrough. In one arrangement, for example, the staples in one line may be substantially parallel with the staples in adjacent line(s) of staples, but offset therefrom. In still other embodiments, one or more lines of staples may be non-linear in nature. That is, the base of at least one staple in a line of staples may extend along an axis that is substantially transverse to the bases of other staples in the same staple line. For example, as will be discussed in further detail below, in alternative embodiments, the lines of staples on each side of the elongated slot may have a zigzag appearance. Such non-linear staple arrangements may attain better tissue fastening results with less staples than various linear staple arrangements employed in prior staple cartridges. 
       FIG. 6  illustrates use of a surgical staple cartridge embodiment  900  in an end effector embodiment  612 ′. As can be seen in  FIGS. 6 and 7 , an embodiment of the surgical staple cartridge  900  has a cartridge body  902  that has a centrally disposed elongated slot  904  extending through a proximal end  903  to an area adjacent a distal end  905 . The elongated slot  904  is configured to permit a knife body to axially move therethrough during a tissue cutting operation in the manner described above. In at least one embodiment, the cartridge body  902  consists of a compressible hemostat material such as, for example, oxidized regenerated cellulose (“ORC”) or a bio-absorbable foam fabricated from, for example, PGA (Polyglycolic acid, sold under the trademark Vicryl), PCL (polycaprolactone), PLA or PLLA (Polyactic acid), PDS, (Polydioxanone), PHA (polyhydroxyalkanoate), PGCL (poliglecaprone 25, sold under the trademark Monocryl) or a composite of PGA, PCL, PLA and PDS in which lines  920 ,  930  of unformed staples  922  are supported. However, the cartridge body  902  may be fabricated from other materials that serve to support the unformed staples  922  in a desired orientation such that they may be compressed as the anvil  910 ′ is brought into contact therewith. As with various other embodiments described above, the staple cartridge  900  is implantable and is left attached to the stapled tissue after the stapling procedure has been completed. In at least some embodiments, in order to prevent the staples  922  from being affected and the hemostat material from being activated during the introduction and positioning process, the entire cartridge  900  may be coated or wrapped in a biodegradable film  906  such as a polydioxanon film sold under the trademark PDS® or with a Polyglycerol sebacate (PGS) film or other biodegradable films fabricated from, for example, PGA (Polyglycolic acid, marketed under the trade mark Vicryl), PCL (Polycaprolactone), PLA or PLLA (Polylactic acid), PHA (polyhydroxyalkanoate), PGCL (poliglecaprone 25, sold under the trademark Monocryl) or a composite of PGA, PCL, PLA, PDS that would be impermeable until ruptured. The cartridge body  902  of staple cartridge  900  is sized to be removably supported within the elongated channel of the end effector  612 ′. 
     In the embodiment depicted in  FIGS. 6, 10, and 11 , the surgical staple cartridge  900  operably supports a first line  920  of staples  922  on one lateral side  907  of the elongated slot  904  and a second line  930  of staples  922  on the other lateral side  909  of the elongated slot  904 . In various embodiments, the staples  922  may be fabricated from a metal material such as, for example, Titanium, Titanium alloys (e.g., 6AI-4V Titanium, 3a1-2.5V Titanium), Stainless Steel, etc. and have a staple base  924  and two upstanding staple legs  926  protruding therefrom. Each staple leg  926  may have a tissue-piercing tip  928  formed thereon. In the first line  920  of staples  922 , the staple base  924  of at least one staple  922  overlaps the staple base of another staple  922 . In a preferred embodiment, the staple base  924  of each staple  922  overlaps the staple bases  924  of two adjacent staples  922 , except for the base  924  of the last staple  922  on each end of the first staple line  920 . See  FIG. 10 . Thus, the first staple line  920  has a substantially non-linear shape. More particularly, when viewed from above, the first staple line  920  has a substantially zigzag appearance. 
     As can be seen in  FIG. 9 , the anvil  90  has two sequential longitudinal staple forming pockets  912  that each has a substantial zigzag shape that corresponds to the shape of the first line  920  of staples  922  such that, when the anvil  910  is brought into forming contact with the staples  922 , the legs  926  thereof are formed as shown in  FIG. 11 . Thus, the distal leg of one staple shares the same pocket as the proximal leg of the next staple longitudinally. Such arrangement allows for a denser pocket pattern, even to a point where the staples themselves interact (e.g., are folded over one another). In prior staple pocket arrangements, in general, there has to be between 0.005 and 0.015 inches of metal/space from one set of pockets to the next. This embodiment of the present invention, however, has a spacing arrangement from 0 to 0.02 inches of interference/overlap (essentially a −0.020″) because one staple mates with the next staple, for example. Such arrangements allow for 15-30% more staples in the same space. Furthermore, when the staples interlock, there is less need for multiple lateral rows of staples. Prior arrangements commonly employ three rows on each side of the tissue cut line to prevent the existing of an open path through which blood may pass. Lines of interlocking staples are less likely to leave paths through which blood may pass. Another distinct advantage provided by the various interlocking staple arrangements of the present invention relates to improved “burst strength” which relates to the amount of force required to tear a staple line open. 
     Another staple forming pocket arrangement may comprise a common staple forming pocket. As used herein, the term “common staple forming pocket” means that one forming pocket can form all of the staples in a single line of staples as opposed to prior anvil designs wherein a discrete forming pocket is provided for each leg of each staple to be formed. 
       FIG. 12  illustrates yet another staple embodiment  922 ′ wherein the base  924 ′ has an offset portion  929  to facilitate a tighter overlap of the bases  924 ′. As indicated above, the staple cartridge  900  has a second line  930  of staples  922  supported on a second lateral side  909  of the elongated slot  904 . The second line  930  of staples  922  is substantially identical to the first line  920  of staples  922 . Thus, the anvil  910  has a second common staple forming pocket  912  that corresponds to the second line of staples  930  for forming contact therewith. In alternative embodiments, however, the second line  930  of staples  922  may differ from the first line  920  of staples in shape and, perhaps, number of staples. 
       FIG. 8  illustrates a surgical staple cartridge  900 ′ that is substantially identical to the staple cartridge  900  described above, with the exception of the lines  920 ′,  930 ′ of staples  922  supported therein. For example, in this embodiment, the line  920 ′ of staples  922  are arranged relative to each other such that a base axis S-S of at least one staple base  924  is substantially transverse to the base axis S-S of the staple base  924  of at least one other adjacent staple  922 . Such predetermined pattern of staples, when viewed from above, comprises a substantially zigzag arrangement. In the embodiment depicted in  FIG. 13 , the respective bases  924  of staples  922  may additionally have a base support member  927  overmolded thereon as shown. In various embodiments, the base support member  927  may be fabricated from, for example, non-absorbable plastic such as Polyether ether ketone “PEEK” or absorbable plastic such as, for example, Polyglycolic acid “PGA”, Polylactic acid “PLA” or “PLLA”, Polydioxanone “PDS”, PCL (polycaprolactone), PHA (polyhydroxyalkanoate), PGCL (poliglecaprone 25, sold under the trademark Monocryl) or various composite mixes if PGS, PDS, PLA, PGA, and PCL. The base support members  927  facilitate interlocking between the staples without making the staples themselves overlap. Thus, such arrangements could form staples with “B” shapes or inverted “W” shapes without the legs of the staples themselves overlapping. However, the crowns are connected by the base support members so they act like overlapping staples. Such arrangements allow the combined pockets to have two discrete paths for each leg. 
     The embodiment depicted in  FIG. 14  employs a staple line  920 ″ wherein the legs  926  of adjacent staples  922  are coupled together by a coupler portion  929  molded or otherwise attached thereto. Each coupler portion  929  may be fabricated from, for example, Polyether ether ketone “PEEK” or absorbable plastic such as, for example, Polyglycolic acid “PGA”, Polylactic acid “PLA” or “PLLA”, Polydioxanone “PDS”, PCL (polycaprolactone), PHA (polyhydroxyalkanoate), PGCL (poliglecaprone 25, sold under the trademark Monocryl) or various composite mixes if PGS, PDS, PLA, PGA, and PCL. Such staple line  920 ″ has substantial zigzag appearance when viewed from above. While the various surgical staple cartridge embodiments  900 ,  900 ′ have been explained with reference to use with the end effector  612 ′, it will be understood that the staple cartridges  900 ,  900 ′ may be effectively employed with the various other end effectors and surgical instruments described hereinabove, with appropriate staple forming pocket arrangements being provided in the anvils of those instruments in order to achieved the desired amount of staple formation upon movement of the anvils into forming contact with the staples. 
       FIGS. 15 and 16  illustrate another surgical staple cartridge  940  embodiment supported in an elongated channel  14  of a surgical instrument  10 . In at least one embodiment, the surgical staple cartridge  940  includes a cartridge body  942  that has a centrally disposed elongated slot  944  extending at least partially therethrough. The elongated slot  944  is configured to permit a knife body of the surgical instrument  10  to axially move therethrough during a tissue cutting operation in the manner described above. In various embodiments, the cartridge body  942  consists of a compressible hemostat material such as, for example, oxidized regenerated cellulose (“ORC”) or a bio-absorbable foam of the types described above or below in which lines  946 ,  948 ,  950 ,  952  of unformed staples  922  are supported. In at least some embodiments, in order to prevent the staples  922  from being affected and the hemostat material from being activated during the introduction and positioning process, the entire cartridge  940  may be coated or wrapped in a biodegradable film  954  such as a polydioxanon film sold under the trademark PDS® or with a Polyglycerol sebacate (PGS) film or other biodegradable films fabricated from, for example, PGA (Polyglycolic acid, marketed under the trade mark Vicryl), PCL (Polycaprolactone), PLA or PLLA (Polylactic acid), PHA (polyhydroxyalkanoate), PGCL (poliglecaprone 25, sold under the trademark Monocryl) or a composite of PGA, PCL, PLA, PDS that would be impermeable until ruptured. 
     In the embodiment depicted in  FIG. 15 , the cartridge  940  further includes a cartridge support member  960  that is coupled to the cartridge body  942 . In various embodiments, the cartridge support member  960  may be fabricated from a rigid material such as, for example, Titanium, Stainless Steel, Aluminum, any alloy of the foregoing, etc. and may be partially embedded within the cartridge body  942 . In various embodiments, the cartridge support member  960  may be held in place by, for example, film  954 . In still other embodiments wherein a limited bond is desired, sporadic use of cyanoacylate could be used to “glue” the two components together. In yet other embodiments, the cartridge body  942  may be heated and “welded” or “fused” to the cartridge support member  960 . In various embodiments, the cartridge support member  960  forms at least a portion of the bottom surface of the cartridge body  942  for mating with the elongated channel  14 . In at least one embodiment, the cartridge support member  960  has one or more snap features  962  protruding therefrom for releasably coupling the cartridge support member  960  to the elongated channel  14 . Other forms of snap features/fastener arrangements may be employed for releasably coupling the cartridge support member  960  to the elongated channel  14 . 
     In various embodiments, the cartridge support member  960  has a series of support ridges  964 ,  966 ,  968 ,  970 ,  972 ,  974 ,  976  formed thereon to provide some lateral support to the bases  924  of the staples  922  in the staple lines  946 ,  948 ,  950 ,  952  as shown in  FIG. 15 . Thus, in at least some embodiments, the support ridges are substantially coextensive with the staple lines.  FIG. 17  illustrates an alternative staple cartridge embodiment  940 ′ that is substantially identical to cartridge  940 , except for the inclusion of upstanding fin portions  978 ,  979 ,  980 ,  981 ,  982 ,  983  that protrude from the support ridges  964 ,  966 ,  968 ,  970 ,  972 ,  976 , respectively to provide additional lateral support to the staples  922 . In various embodiments, the fin portions may be integrally formed with the cartridge support member  960  and have a height that is about ½ or less of the height of the cartridge. Thus, in various embodiments, for example, any standing features supporting the foam cannot extend above the maximum compression height of the foam. Thus, if the cartridge is designed, for example, to compress to ⅓ of its original height when fired, the fins would between 66% of the uncompressed height, all the way down to 10% of uncompressed height. 
     In use, once the staples  922  have been formed through contact with the anvil  20  in the manner described above, the anvil  20  is opened and the end effector  12  is pulled away from the stapled tissue. As the end effector  12  is pulled away from the stapled tissue, the cartridge body  942  remains fastened to the stapled tissue and is then separated from the cartridge support member  960  which remains coupled to the elongated channel  14 . In various embodiments, the cartridge support member  960  is provided with a color that differs from the color of the material comprising the cartridge body  942  as well as the color of the elongated channel  14 . Such arrangement provides the surgeon with an easily recognizable indication that no staple cartridge is present within the end effector. Thus, the surgeon will not inadvertently attempt to reinsert/use the end effector without first installing a new staple cartridge therein. To do so, the surgeon simply disconnects the snap features of the cartridge support member  960  from the elongated channel  14  to enable the cartridge support member  960  of a new staple cartridge  940  to be placed therein. While the staple cartridges  940 ,  940 ′ have been explained with reference to surgical instrument  10 , it will be understood that those cartridges may be effectively employed with many of the other surgical instrument embodiments disclosed herein without departing from the spirit and scope of the present invention. 
     In various embodiments, a staple cartridge can comprise a cartridge body and a plurality of staples stored within the cartridge body. In use, the staple cartridge can be introduced into a surgical site and positioned on a side of the tissue being treated. In addition, a staple-forming anvil can be positioned on the opposite side of the tissue. In various embodiments, the anvil can be carried by a first jaw and the staple cartridge can be carried by a second jaw, wherein the first jaw and/or the second jaw can be moved toward the other. Once the staple cartridge and the anvil have been positioned relative to the tissue, the staples can be ejected from the staple cartridge body such that the staples can pierce the tissue and contact the staple-forming anvil. Once the staples have been deployed from the staple cartridge body, the staple cartridge body can then be removed from the surgical site. In various embodiments disclosed herein, a staple cartridge, or at least a portion of a staple cartridge, can be implanted with the staples. In at least one such embodiment, as described in greater detail further below, a staple cartridge can comprise a cartridge body which can be compressed, crushed, and/or collapsed by the anvil when the anvil is moved from an open position into a closed position. When the cartridge body is compressed, crushed, and/or collapsed, the staples positioned within the cartridge body can be deformed by the anvil. Alternatively, the jaw supporting the staple cartridge can be moved toward the anvil into a closed position. In either event, in various embodiments, the staples can be deformed while they are at least partially positioned within the cartridge body. In certain embodiments, the staples may not be ejected from the staple cartridge while, in some embodiments, the staples can be ejected from the staple cartridge along with a portion of the cartridge body. 
     Referring now to  FIGS. 18A-18D , a compressible staple cartridge, such as staple cartridge  1000 , for example, can comprise a compressible, implantable cartridge body  1010  and, in addition, a plurality of staples  1020  positioned in the compressible cartridge body  1010 , although only one staple  1020  is depicted in  FIGS. 18A-18D .  FIG. 18A  illustrates the staple cartridge  1000  supported by a staple cartridge support, or staple cartridge channel,  1030 , wherein the staple cartridge  1000  is illustrated in an uncompressed condition. In such an uncompressed condition, the anvil  1040  may or may not be in contact with the tissue T. In use, the anvil  1040  can be moved from an open position into contact with the tissue T as illustrated in  FIG. 18B  and position the tissue T against the cartridge body  1010 . Even though the anvil  1040  can position the tissue T against a tissue-contacting surface  1019  of staple cartridge body  1010 , referring again to  FIG. 18B , the staple cartridge body  1010  may be subjected to little, if any, compressive force or pressure at such point and the staples  1020  may remain in an unformed, or unfired, condition. As illustrated in  FIGS. 18A and 18B , the staple cartridge body  1010  can comprise one or more layers and the staple legs  1021  of staples  1020  can extend upwardly through these layers. In various embodiments, the cartridge body  1010  can comprise a first layer  1011 , a second layer  1012 , a third layer  1013 , wherein the second layer  1012  can be positioned intermediate the first layer  1011  and the third layer  1013 , and a fourth layer  1014 , wherein the third layer  1013  can be positioned intermediate the second layer  1012  and the fourth layer  1014 . In at least one embodiment, the bases  1022  of the staples  1020  can be positioned within cavities  1015  in the fourth layer  1014  and the staple legs  1021  can extend upwardly from the bases  1022  and through the fourth layer  1014 , the third layer  1013 , and the second layer  1012 , for example. In various embodiments, each deformable leg  1021  can comprise a tip, such as sharp tip  1023 , for example, which can be positioned in the second layer  1012 , for example, when the staple cartridge  1000  is in an uncompressed condition. In at least one such embodiment, the tips  1023  may not extend into and/or through the first layer  1011 , wherein, in at least one embodiment, the tips  1023  may not protrude through the tissue-contacting surface  1019  when the staple cartridge  1000  is in an uncompressed condition. In certain other embodiments, the sharp tips  1023  may be positioned in the third layer  1013 , and/or any other suitable layer, when the staple cartridge is in an uncompressed condition. In various alternative embodiments, a cartridge body of a staple cartridge may have any suitable number of layers such as less than four layers or more than four layers, for example. 
     In various embodiments, as described in greater detail below, the first layer  1011  can be comprised of a buttress material and/or plastic material, such as polydioxanone (PDS) and/or polyglycolic acid (PGA), for example, and the second layer  1012  can be comprised of a bioabsorbable foam material and/or a compressible haemostatic material, such as oxidized regenerated cellulose (ORC), for example. In various embodiments, one or more of the first layer  1011 , the second layer  1012 , the third layer  1013 , and the fourth layer  1014  may hold the staples  1020  within the staple cartridge body  1010  and, in addition, maintain the staples  1020  in alignment with one another. In various embodiments, the third layer  1013  can be comprised of a buttress material, or a fairly incompressible or inelastic material, which can be configured to hold the staple legs  1021  of the staples  1020  in position relative to one another. Furthermore, the second layer  1012  and the fourth layer  1014 , which are positioned on opposite sides of the third layer  1013 , can stabilize, or reduce the movement of, the staples  1020  even though the second layer  1012  and the fourth layer  1014  can be comprised of a compressible foam or elastic material. In certain embodiments, the staple tips  1023  of the staple legs  1021  can be at least partially embedded in the first layer  1011 . In at least one such embodiment, the first layer  1011  and the third layer  1013  can be configured to co-operatively and firmly hold the staple legs  1021  in position. In at least one embodiment, the first layer  1011  and the third layer  1013  can each be comprised of a sheet of bioabsorbable plastic, such as polyglycolic acid (PGA) which is marketed under the trade name Vicryl, polylactic acid (PLA or PLLA), polydioxanone (PDS), polyhydroxyalkanoate (PHA), poliglecaprone 25 (PGCL) which is marketed under the trade name Monocryl, polycaprolactone (PCL), and/or a composite of PGA, PLA, PDS, PHA, PGCL and/or PCL, for example, and the second layer  1012  and the fourth layer  1014  can each be comprised of at least one haemostatic material or agent. 
     Although the first layer  1011  can be compressible, the second layer  1012  can be substantially more compressible than the first layer  1011 . For example, the second layer  1012  can be about twice as compressible, about three times as compressible, about four times as compressible, about five times as compressible, and/or about ten times as compressible, for example, as the first layer  1011 . Stated another way, the second layer  1012  may compress about two times, about three times, about four times, about five times, and/or about ten times as much as first layer  1011 , for a given force. In certain embodiments, the second layer  1012  can be between about twice as compressible and about ten times as compressible, for example, as the first layer  1011 . In at least one embodiment, the second layer  1012  can comprise a plurality of air voids defined therein, wherein the amount and/or size of the air voids in the second layer  1012  can be controlled in order to provide a desired compressibility of the second layer  1012 . Similar to the above, although the third layer  1013  can be compressible, the fourth layer  1014  can be substantially more compressible than the third layer  1013 . For example, the fourth layer  1014  can be about twice as compressible, about three times as compressible, about four times as compressible, about five times as compressible, and/or about ten times as compressible, for example, as the third layer  1013 . Stated another way, the fourth layer  1014  may compress about two times, about three times, about four times, about five times, and/or about ten times as much as third layer  1013 , for a given force. In certain embodiments, the fourth layer  1014  can be between about twice as compressible and about ten times as compressible, for example, as the third layer  1013 . In at least one embodiment, the fourth layer  1014  can comprise a plurality of air voids defined therein, wherein the amount and/or size of the air voids in the fourth layer  1014  can be controlled in order to provide a desired compressibility of the fourth layer  1014 . In various circumstances, the compressibility of a cartridge body, or cartridge body layer, can be expressed in terms of a compression rate, i.e., a distance in which a layer is compressed for a given amount of force. For example, a layer having a high compression rate will compress a larger distance for a given amount of compressive force applied to the layer as compared to a layer having a lower compression rate. This being said, the second layer  1012  can have a higher compression rate than the first layer  1011  and, similarly, the fourth layer  1014  can have a higher compression rate than the third layer  1013 . In various embodiments, the second layer  1012  and the fourth layer  1014  can be comprised of the same material and can comprise the same compression rate. In various embodiments, the second layer  1012  and the fourth layer  1014  can be comprised of materials having different compression rates. Similarly, the first layer  1011  and the third layer  1013  can be comprised of the same material and can comprise the same compression rate. In certain embodiments, the first layer  1011  and the third layer  1013  can be comprised of materials having different compression rates. 
     As the anvil  1040  is moved toward its closed position, the anvil  1040  can contact tissue T and apply a compressive force to the tissue T and the staple cartridge  1000 , as illustrated in  FIG. 18C . In such circumstances, the anvil  1040  can push the top surface, or tissue-contacting surface  1019 , of the cartridge body  1010  downwardly toward the staple cartridge support  1030 . In various embodiments, the staple cartridge support  1030  can comprise a cartridge support surface  1031  which can be configured to support the staple cartridge  1000  as the staple cartridge  1000  is compressed between the cartridge support surface  1031  and the tissue-contacting surface  1041  of anvil  1040 . Owing to the pressure applied by the anvil  1040 , the cartridge body  1010  can be compressed and the anvil  1040  can come into contact with the staples  1020 . More particularly, in various embodiments, the compression of the cartridge body  1010  and the downward movement of the tissue-contacting surface  1019  can cause the tips  1023  of the staple legs  1021  to pierce the first layer  1011  of cartridge body  1010 , pierce the tissue T, and enter into forming pockets  1042  in the anvil  1040 . As the cartridge body  1010  is further compressed by the anvil  1040 , the tips  1023  can contact the walls defining the forming pockets  1042  and, as a result, the legs  1021  can be deformed or curled inwardly, for example, as illustrated in  FIG. 18C . As the staple legs  1021  are being deformed, as also illustrated in  FIG. 18C , the bases  1022  of the staples  1020  can be in contact with or supported by the staple cartridge support  1030 . In various embodiments, as described in greater detail below, the staple cartridge support  1030  can comprise a plurality of support features, such as staple support grooves, slots, or troughs  1032 , for example, which can be configured to support the staples  1020 , or at least the bases  1022  of the staples  1020 , as the staples  1020  are being deformed. As also illustrated in  FIG. 18C , the cavities  1015  in the fourth layer  1014  can collapse as a result of the compressive force applied to the staple cartridge body  1010 . In addition to the cavities  1015 , the staple cartridge body  1010  can further comprise one or more voids, such as voids  1016 , for example, which may or may not comprise a portion of a staple positioned therein, that can be configured to allow the cartridge body  1010  to collapse. In various embodiments, the cavities  1015  and/or the voids  1016  can be configured to collapse such that the walls defining the cavities and/or walls deflect downwardly and contact the cartridge support surface  1031  and/or contact a layer of the cartridge body  1010  positioned underneath the cavities and/or voids. 
     Upon comparing  FIG. 18B  and  FIG. 18C , it is evident that the second layer  1012  and the fourth layer  1014  have been substantially compressed by the compressive pressure applied by the anvil  1040 . It may also be noted that the first layer  1011  and the third layer  1013  have been compressed as well. As the anvil  1040  is moved into its closed position, the anvil  1040  may continue to further compress the cartridge body  1010  by pushing the tissue-contacting surface  1019  downwardly toward the staple cartridge support  1030 . As the cartridge body  1010  is further compressed, the anvil  1040  can deform the staples  1020  into their completely-formed shape as illustrated in  FIG. 18D . Referring to  FIG. 18D , the legs  1021  of each staple  1020  can be deformed downwardly toward the base  1022  of each staple  1020  in order to capture at least a portion of the tissue T, the first layer  1011 , the second layer  1012 , the third layer  1013 , and the fourth layer  1014  between the deformable legs  1021  and the base  1022 . Upon comparing  FIGS. 18C and 18D , it is further evident that the second layer  1012  and the fourth layer  1014  have been further substantially compressed by the compressive pressure applied by the anvil  1040 . It may also be noted upon comparing  FIGS. 18C and 18D  that the first layer  1011  and the third layer  1013  have been further compressed as well. After the staples  1020  have been completely, or at least sufficiently, formed, the anvil  1040  can be lifted away from the tissue T and the staple cartridge support  1030  can be moved away, and/or detached from, the staple cartridge  1000 . As depicted in  FIG. 18D , and as a result of the above, the cartridge body  1010  can be implanted with the staples  1020 . In various circumstances, the implanted cartridge body  1010  can support the tissue along the staple line. In some circumstances, a haemostatic agent, and/or any other suitable therapeutic medicament, contained within the implanted cartridge body  1010  can treat the tissue over time. A haemostatic agent, as mentioned above, can reduce the bleeding of the stapled and/or incised tissue while a bonding agent or tissue adhesive can provide strength to the tissue over time. The implanted cartridge body  1010  can be comprised of materials such as ORC (oxidized regenerated cellulous), protein matrix, polyglycolic acid (PGA) which is marketed under the trade name Vicryl, polylactic acid (PLA or PLLA), polydioxanone (PDS), polyhydroxyalkanoate (PHA), poliglecaprone 25 (PGCL) which is marketed under the trade name Monocryl, polycaprolactone (PCL), and/or a composite of PGA, PLA, PDS, PHA, PGCL and/or PCL, for example. In certain circumstances, the cartridge body  1010  can comprise an antibiotic and/or anti-microbial material, such as colloidal silver and/or triclosan, for example, which can reduce the possibility of infection in the surgical site. 
     In various embodiments, the layers of the cartridge body  1010  can be connected to one another. In at least one embodiment, the second layer  1012  can be adhered to the first layer  1011 , the third layer  1013  can be adhered to the second layer  1012 , and the fourth layer  1014  can be adhered to the third layer  1013  utilizing at least one adhesive, such as fibrin and/or protein hydrogel, for example. In certain embodiments, although not illustrated, the layers of the cartridge body  1010  can be connected together by interlocking mechanical features. In at least one such embodiment, the first layer  1011  and the second layer  1012  can each comprise corresponding interlocking features, such as a tongue and groove arrangement and/or a dovetail joint arrangement, for example. Similarly, the second layer  1012  and the third layer  1013  can each comprise corresponding interlocking features while the third layer  1013  and the fourth layer  1014  can each comprise corresponding interlocking features. In certain embodiments, although not illustrated, the staple cartridge  1000  can comprise one or more rivets, for example, which can extend through one or more layers of the cartridge body  1010 . In at least one such embodiment, each rivet can comprise a first end, or head, positioned adjacent to the first layer  1011  and a second head positioned adjacent to the fourth layer  1014  which can be either assembled to or formed by a second end of the rivet. Owing to the compressible nature of the cartridge body  1010 , in at least one embodiment, the rivets can compress the cartridge body  1010  such that the heads of the rivets can be recessed relative to the tissue-contacting surface  1019  and/or the bottom surface  1018  of the cartridge body  1010 , for example. In at least one such embodiment, the rivets can be comprised of a bioabsorbable material, such as polyglycolic acid (PGA) which is marketed under the trade name Vicryl, polylactic acid (PLA or PLLA), polydioxanone (PDS), polyhydroxyalkanoate (PHA), poliglecaprone 25 (PGCL) which is marketed under the trade name Monocryl, polycaprolactone (PCL), and/or a composite of PGA, PLA, PDS, PHA, PGCL and/or PCL, for example. In certain embodiments, the layers of the cartridge body  1010  may not be connected to one another other than by the staples  1020  contained therein. In at least one such embodiment, the frictional engagement between the staple legs  1021  and the cartridge body  1010 , for example, can hold the layers of the cartridge body  1010  together and, once the staples have been formed, the layers can be captured within the staples  1020 . In certain embodiments, at least a portion of the staple legs  1021  can comprise a roughened surface or rough coating which can increase the friction forces between the staples  1020  and the cartridge body  1010 . 
     As described above, a surgical instrument can comprise a first jaw including the staple cartridge support  1030  and a second jaw including the anvil  1040 . In various embodiments, as described in greater detail further below, the staple cartridge  1000  can comprise one or more retention features which can be configured to engage the staple cartridge support  1030  and, as a result, releasably retain the staple cartridge  1000  to the staple cartridge support  1030 . In certain embodiments, the staple cartridge  1000  can be adhered to the staple cartridge support  1030  by at least one adhesive, such as fibrin and/or protein hydrogel, for example. In use, in at least one circumstance, especially in laparoscopic and/or endoscopic surgery, the second jaw can be moved into a closed position opposite the first jaw, for example, such that the first and second jaws can be inserted through a trocar into a surgical site. In at least one such embodiment, the trocar can define an approximately 5 mm aperture, or cannula, through which the first and second jaws can be inserted. In certain embodiments, the second jaw can be moved into a partially-closed position intermediate the open position and the closed position which can allow the first and second jaws to be inserted through the trocar without deforming the staples  1020  contained in the staple cartridge body  1010 . In at least one such embodiment, the anvil  1040  may not apply a compressive force to the staple cartridge body  1010  when the second jaw is in its partially-closed intermediate position while, in certain other embodiments, the anvil  1040  can compress the staple cartridge body  1010  when the second jaw is in its partially-closed intermediate position. Even though the anvil  1040  can compress the staple cartridge body  1010  when it is in such an intermediate position, the anvil  1040  may not sufficiently compress the staple cartridge body  1010  such that the anvil  1040  comes into contact with the staples  1020  and/or such that the staples  1020  are deformed by the anvil  1040 . Once the first and second jaws have been inserted through the trocar into the surgical site, the second jaw can be opened once again and the anvil  1040  and the staple cartridge  1000  can be positioned relative to the targeted tissue as described above. 
     In various embodiments, referring now to  FIGS. 19A-19D , an end effector of a surgical stapler can comprise an implantable staple cartridge  1100  positioned intermediate an anvil  1140  and a staple cartridge support  1130 . Similar to the above, the anvil  1140  can comprise a tissue-contacting surface  1141 , the staple cartridge  1100  can comprise a tissue-contacting surface  1119 , and the staple cartridge support  1130  can comprise a support surface  1131  which can be configured to support the staple cartridge  1100 . Referring to  FIG. 19A , the anvil  1140  can be utilized to position the tissue T against the tissue contacting surface  1119  of staple cartridge  1100  without deforming the staple cartridge  1100  and, when the anvil  1140  is in such a position, the tissue-contacting surface  1141  can be positioned a distance  1101   a  away from the staple cartridge support surface  1131  and the tissue-contacting surface  1119  can be positioned a distance  1102   a  away from the staple cartridge support surface  1131 . Thereafter, as the anvil  1140  is moved toward the staple cartridge support  1130 , referring now to  FIG. 19B , the anvil  1140  can push the top surface, or tissue-contacting surface  1119 , of staple cartridge  1100  downwardly and compress the first layer  1111  and the second layer  1112  of cartridge body  1110 . As the layers  1111  and  1112  are compressed, referring again to  FIG. 19B , the second layer  1112  can be crushed and the legs  1121  of staples  1120  can pierce the first layer  1111  and enter into the tissue T. In at least one such embodiment, the staples  1120  can be at least partially positioned within staple cavities, or voids,  1115  in the second layer  1112  and, when the second layer  1112  is compressed, the staple cavities  1115  can collapse and, as a result, allow the second layer  1112  to collapse around the staples  1120 . In various embodiments, the second layer  1112  can comprise cover portions  1116  which can extend over the staple cavities  1115  and enclose, or at least partially enclose, the staple cavities  1115 .  FIG. 19B  illustrates the cover portions  1116  being crushed downwardly into the staple cavities  1115 . In certain embodiments, the second layer  1112  can comprise one or more weakened portions which can facilitate the collapse of the second layer  1112 . In various embodiments, such weakened portions can comprise score marks, perforations, and/or thin cross-sections, for example, which can facilitate a controlled collapse of the cartridge body  1110 . In at least one embodiment, the first layer  1111  can comprise one or more weakened portions which can facilitate the penetration of the staple legs  1121  through the first layer  1111 . In various embodiments, such weakened portions can comprise score marks, perforations, and/or thin cross-sections, for example, which can be aligned, or at least substantially aligned, with the staple legs  1121 . 
     When the anvil  1140  is in a partially closed, unfired position, referring again to  FIG. 19A , the anvil  1140  can be positioned a distance  1101   a  away from the cartridge support surface  1131  such that a gap is defined therebetween. This gap can be filled by the staple cartridge  1100 , having a staple cartridge height  1102   a , and the tissue T. As the anvil  1140  is moved downwardly to compress the staple cartridge  1100 , referring again to  FIG. 19B , the distance between the tissue contacting surface  1141  and the cartridge support surface  1131  can be defined by a distance  1101   b  which is shorter than the distance  1101   a . In various circumstances, the gap between the tissue-contacting surface  1141  of anvil  1140  and the cartridge support surface  1131 , defined by distance  1101   b , may be larger than the original, undeformed staple cartridge height  1102   a . As the anvil  1140  is moved closer to the cartridge support surface  1131 , referring now to  FIG. 19C , the second layer  1112  can continue to collapse and the distance between the staple legs  1121  and the forming pockets  1142  can decrease. Similarly, the distance between the tissue-contacting surface  1141  and the cartridge support surface  1131  can decrease to a distance  1101   c  which, in various embodiments, may be greater than, equal to, or less than the original, undeformed cartridge height  1102   a . Referring now to  FIG. 19D , the anvil  1140  can be moved into a final, fired position in which the staples  1120  have been fully formed, or at least formed to a desired height. In such a position, the tissue-contacting surface  1141  of anvil  1140  can be a distance  1101   d  away from the cartridge support surface  1131 , wherein the distance  1101   d  can be shorter than the original, undeformed cartridge height  1102   a . As also illustrated in  FIG. 19D , the staple cavities  1115  may be fully, or at least substantially, collapsed and the staples  1120  may be completely, or at least substantially, surrounded by the collapsed second layer  1112 . In various circumstances, the anvil  1140  can be thereafter moved away from the staple cartridge  1100 . Once the anvil  1140  has been disengaged from the staple cartridge  1100 , the cartridge body  1110  can at least partially re-expand in various locations, i.e., locations intermediate adjacent staples  1120 , for example. In at least one embodiment, the crushed cartridge body  1110  may not resiliently re-expand. In various embodiments, the formed staples  1120  and, in addition, the cartridge body  1110  positioned intermediate adjacent staples  1120  may apply pressure, or compressive forces, to the tissue T which may provide various therapeutic benefits. 
     As discussed above, referring again to the embodiment illustrated in  FIG. 19A , each staple  1120  can comprise staple legs  1121  extending therefrom. Although staples  1120  are depicted as comprising two staple legs  1121 , various staples can be utilized which can comprise one staple leg or, alternatively, more than two staple legs, such as three staple legs or four staple legs, for example. As illustrated in  FIG. 19A , each staple leg  1121  can be embedded in the second layer  1112  of the cartridge body  1110  such that the staples  1120  are secured within the second layer  1112 . In various embodiments, the staples  1120  can be inserted into the staple cavities  1115  in cartridge body  1110  such that the tips  1123  of the staple legs  1121  enter into the cavities  1115  before the bases  1122 . After the tips  1123  have been inserted into the cavities  1115 , in various embodiments, the tips  1123  can be pressed into the cover portions  1116  and incise the second layer  1112 . In various embodiments, the staples  1120  can be seated to a sufficient depth within the second layer  1112  such that the staples  1120  do not move, or at least substantially move, relative to the second layer  1112 . In certain embodiments, the staples  1120  can be seated to a sufficient depth within the second layer  1112  such that the bases  1122  are positioned or embedded within the staple cavities  1115 . In various other embodiments, the bases  1122  may not be positioned or embedded within the second layer  1112 . In certain embodiments, referring again to  FIG. 19A , the bases  1122  may extend below the bottom surface  1118  of the cartridge body  1110 . In certain embodiments, the bases  1122  can rest on, or can be directly positioned against, the cartridge support surface  1130 . In various embodiments, the cartridge support surface  1130  can comprise support features extending therefrom and/or defined therein wherein, in at least one such embodiment, the bases  1122  of the staples  1120  may be positioned within and supported by one or more support grooves, slots, or troughs,  1132 , for example, in the staple cartridge support  1130 , as described in greater detail further below. 
     Further to the above, referring now to  FIG. 20 , the bases  1122  of the staples  1120  can be positioned directly against the support surface  1131  of staple cartridge support  1130 . In various embodiments, including embodiments where the staple bases  1122  comprise circular or arcuate bottom surfaces  1124 , for example, the staple bases  1122  may move or slide along the staple cartridge support surface  1131 . Such sliding can occur when the anvil  1140  is pressed against the tips  1123  of the staple legs  1121  during the staple forming process. In certain embodiments, as described above and referring now to  FIG. 21 , the staple cartridge support  1130  can comprise one or more support slots  1132  therein which can be configured to eliminate, or at least reduce, the relative movement between the staple bases  1122  and the cartridge support surface  1131 . In at least one such embodiment, each support slot  1132  can be defined by a surface contour which matches, or at least substantially matches, the contour of the bottom surface of the staple positioned therein. For example, the bottom surface  1124  of the base  1122  depicted in  FIG. 21  can comprise a circular, or at least substantially circular, surface and the support slot  1132  can also comprise a circular, or at least substantially circular, surface. In at least one such embodiment, the surface defining the slot  1132  can be defined by a radius of curvature which is greater than or equal to a radius of curvature which defines bottom surface  1124 . Although the slots  1132  may assist in preventing or reducing relative sliding movement between the staples  1120  and the staple cartridge support  1130 , the slots  1132  may also be configured to prevent or reduce relative rotational movement between the staples  1120  and the staple cartridge support  1130 . More particularly, in at least one embodiment, the slots  1132  can be configured to closely receive the bases  1122  in order to prevent or reduce the rotation of the staples  1120  about axes  1129 , for example, such that the staples  1120  do not rotate or twist when they are being deformed. 
     In various embodiments, further to the above, each staple  1120  can be formed from a round, or an at least substantially round, wire. In certain embodiments, the legs and the base of each staple can be formed from a wire having a non-circular cross-section, such as a rectangular cross-section, for example. In at least one such embodiment, the staple cartridge support  1130  can comprise corresponding non-circular slots, such as rectangular slots, for example, configured to receive the bases of such staples. In various embodiments, referring now to  FIG. 22 , each staple  1120  can comprise a crown, such as a crown  1125 , for example, overmolded onto a base  1122  wherein each crown  1125  can be positioned within a support slot in the staple cartridge support  1130 . In at least one such embodiment, each crown  1125  can comprise a square and/or rectangular cross-section, for example, which can be configured to be received within square and/or rectangular slots  1134 , for example, in the staple cartridge support  1130 . In various embodiments, the crowns  1125  can be comprised of a bioabsorbable plastic, such as polyglycolic acid (PGA) which is marketed under the trade name Vicryl, polylactic acid (PLA or PLLA), polydioxanone (PDS), polyhydroxyalkanoate (PHA), poliglecaprone 25 (PGCL) which is marketed under the trade name Monocryl, polycaprolactone (PCL), and/or a composite of PGA, PLA, PDS, PHA, PGCL and/or PCL, for example, and can be formed around the bases  1122  of the staples  1120  by an injection molding process, for example. Various crowns and methods for forming various crowns are disclosed in U.S. patent application Ser. No. 11/541,123, entitled SURGICAL STAPLES HAVING COMPRESSIBLE OR CRUSHABLE MEMBERS FOR SECURING TISSUE THEREIN AND STAPLING INSTRUMENTS FOR DEPLOYING THE SAME, filed on Sep. 29, 2006, now U.S. Pat. No. 7,794,475, the entire disclosure of which is incorporated be reference herein. Referring again to  FIG. 22 , the slots  1134  can further comprise lead-ins, or bevels,  1135  which can be configured to facilitate the insertion of the crowns  1125  into the slots  1134 . In various embodiments, the bases and/or crowns of the staples  1120  may be positioned within the slots  1134  when the staple cartridge  1100  is assembled to the staple cartridge support  1130 . In certain embodiments, the crowns  1125  of the staples  1120  may be aligned with the slots  1134  when the staple cartridge  1100  is assembled to the staple cartridge support  1130 . In at least one such embodiment, the crowns  1125  may not enter into the slots  1134  until a compressive force is applied to the staple legs  1121  and the bases and/or crowns of the staples  1120  are pushed downwardly into the slots  1134 . 
     In various embodiments, referring now to  FIGS. 23 and 24 , a staple cartridge, such as staple cartridge  1200 , for example, can comprise a compressible, implantable cartridge body  1210  comprising an outer layer  1211  and an inner layer  1212 . Similar to the above, the staple cartridge  1200  can comprise a plurality of staples  1220  positioned within the cartridge body  1210 . In various embodiments, each staple  1220  can comprise a base  1222  and one or more staple legs  1221  extending therefrom. In at least one such embodiment, the staple legs  1221  can be inserted into the inner layer  1212  and seated to a depth in which the bases  1222  of the staples  1220  abut and/or are positioned adjacent to the bottom surface  1218  of the inner layer  1212 , for example. In the embodiment depicted in  FIGS. 23 and 24 , the inner layer  1212  does not comprise staple cavities configured to receive a portion of the staples  1220  while, in other embodiments, the inner layer  1212  can comprise such staple cavities. In various embodiments, further to the above, the inner layer  1212  can be comprised of a compressible material, such as bioabsorbable foam and/or oxidized regenerated cellulose (ORC), for example, which can be configured to allow the cartridge body  1210  to collapse when a compressive load is applied thereto. In various embodiments, the inner layer  1212  can be comprised of a lyophilized foam comprising polylactic acid (PLA) and/or polyglycolic acid (PGA), for example. The ORC may be commercially available under the trade name Surgicel and can comprise a loose woven fabric (like a surgical sponge), loose fibers (like a cotton ball), and/or a foam. In at least one embodiment, the inner layer  1212  can be comprised of a material including medicaments, such as freeze-dried thrombin and/or fibrin, for example, contained therein and/or coated thereon which can be water-activated and/or activated by fluids within the patient&#39;s body, for example. In at least one such embodiment, the freeze-dried thrombin and/or fibrin can be held on a Vicryl (PGA) matrix, for example. In certain circumstances, however, the activatable medicaments can be unintentionally activated when the staple cartridge  1200  is inserted into a surgical site within the patient, for example. In various embodiments, referring again to  FIGS. 23 and 24 , the outer layer  1211  can be comprised of a water impermeable, or at least substantially water impermeable, material such that liquids do not come into contact with, or at least substantially contact, the inner layer  1212  until after the cartridge body  1210  has been compressed and the staple legs have penetrated the outer layer  1211  and/or after the outer layer  1211  has been incised in some fashion. In various embodiments, the outer layer  1211  can be comprised of a buttress material and/or plastic material, such as polydioxanone (PDS) and/or polyglycolic acid (PGA), for example. In certain embodiments, the outer layer  1211  can comprise a wrap which surrounds the inner layer  1212  and the staples  1220 . More particularly, in at least one embodiment, the staples  1220  can be inserted into the inner layer  1212  and the outer layer  1211  can be wrapped around the sub-assembly comprising the inner layer  1212  and the staples  1220  and then sealed. 
     In various embodiments, referring now to  FIGS. 25 and 26 , a staple cartridge, such as staple cartridge  1300 , for example, can comprise a compressible, implantable cartridge body  1310  including an outer layer  1311  and an inner layer  1312 . Similar to the above, the staple cartridge  1300  can further comprise staples  1320  positioned within the cartridge body  1310  wherein each staple  1320  can comprise a base  1322  and one or more legs  1321  extending therefrom. Similar to staple cartridge  1200 , the bases  1322  of staples  1320  can extend below the bottom surface  1318  of the inner layer  1312  and the outer layer  1311  can surround the bases  1322 . In at least one such embodiment, the outer layer  1311  can be sufficiently flexible so as to envelop each staple base  1322  such that the outer layer  1311  conforms to the contour of the bases  1322 . In at least one alternative embodiment, referring again to  FIG. 24 , the outer layer  1211  can be sufficiently rigid such that it extends around the bases  1222  without conforming to each base  1222 . In any event, in various embodiments, the outer layer  1311  can be positioned intermediate the bases  1322  of staples  1320  and a staple cartridge support surface, such as support surfaces  1031  or  1131 , for example, supporting the staple cartridge  1300 . In at least one such embodiment, the outer layer  1311  can be positioned intermediate the bases  1322  and support slots, such as slots  1032  or  1132 , for example, defined in the staple cartridge support surface. In at least one such embodiment, further to the above, the outer layer  1311  can be configured to limit the movement of the bases  1322  and/or increase the coefficient of friction between the bases  1322  and the staple cartridge support surface and/or support slots in order to reduce relative movement therebetween. In various alternative embodiments, referring now to  FIGS. 27 and 28 , the outer layer of a staple cartridge, such as staple cartridge  1400 , for example, may not entirely surround the staples positioned therein. In at least one such embodiment, an outer layer  1411  of a compressible, implantable cartridge body  1410  may be assembled to the inner layer  1412  before the staple legs  1421  of staples  1420  are inserted into the cartridge body  1410 . As a result of the above, the bases  1422  of staples  1420  may extend outside of the outer layer  1411  and, in at least one such embodiment, the bases  1422  may be positioned directly into the support slots  1032  or  1132  within the staple cartridge support surfaces  1031  or  1131 , for example. In various embodiments, the staple legs  1421  may incise the outer layer  1411  when they are inserted therethrough. In various circumstances, the holes created by the staple legs  1421  may closely surround the staple legs  1421  such that very little, if any, fluid can leak between the staple legs  1421  and the outer layer  1411  which can reduce the possibility of, or prevent, the medicament contained within the staple cartridge body  1410  from being activated and/or leaking out of the cartridge body  1410  prematurely. 
     As discussed above, referring again to  FIGS. 23 and 24 , the legs  1221  of the staples  1220  can be embedded within the cartridge body  1210  and the bases  1222  of staples  1220  may extend outwardly from the bottom surface  1218  of the inner layer  1212 . In various embodiments, further to the above, the inner layer  1212  may not comprise staple cavities configured to receive the staples  1220 . In various other embodiments, referring now to  FIGS. 29 and 30 , a staple cartridge, such as staple cartridge  1500 , for example, may comprise a compressible, implantable cartridge body  1510  comprising staple cavities  1515  which can be configured to receive at least a portion of the staples  1520  therein. In at least one such embodiment, a top portion of the staple legs  1521  of the staples  1520  may be embedded in the inner layer  1512  while a bottom portion of the staple legs  1521 , and the bases  1522 , may be positioned within the staple cavities  1515 . In certain embodiments, the bases  1522  may be entirely positioned in the staple cavities  1515  while, in some embodiments, the bases  1522  may at least partially extend below the bottom surface  1518  of the inner layer  1512 . Similar to the above, the outer layer  1511  may enclose the inner layer  1512  and the staples  1520  positioned therein. In certain other embodiments, referring now to  FIG. 31 , a staple cartridge  1600  may comprise staples  1620  positioned within staple cavities  1615  in a compressible, implantable cartridge body  1610  wherein at least a portion of the staples  1620  are not enclosed by the outer layer  1611 . In at least one such embodiment, each staple  1620  can comprise staple legs  1621  which are at least partially embedded in the inner layer  1612  and, in addition, bases  1622  which extend outwardly around the outer layer  1611 . 
     In various embodiments, referring now to  FIGS. 32 and 33 , a staple cartridge, such as staple cartridge  1700 , for example, can comprise a compressible, implantable cartridge body  1710  and a plurality of staples  1720  at least partially positioned within the cartridge body  1710 . The cartridge body  1710  can comprise an outer layer  1711 , an inner layer  1712 , and, in addition, an alignment matrix  1740  which can be configured to align and/or retain the staples  1720  in position within the cartridge body  1710 . In at least one embodiment, the inner layer  1712  can comprise a recess  1741  which can be configured to receive the alignment matrix  1740  therein. In various embodiments, the alignment matrix  1140  can be press-fit within the recess  1741  and/or otherwise suitably secured to the inner layer  1712  utilizing at least one adhesive, such as fibrin and/or protein hydrogel, for example. In at least one embodiment, the recess  1741  can be configured such that the bottom surface  1742  of alignment matrix  1740  is aligned, or at least substantially aligned, with the bottom surface  1718  of the inner layer  1712 . In certain embodiments, the bottom surface  1742  of the alignment matrix can be recessed with respect to and/or extend from the bottom surface  1718  of the second layer  1712 . In various embodiments, each staple  1720  can comprise a base  1722  and one or more legs  1721  extending from the base  1722 , wherein at least a portion of the staple legs  1721  can extend through the alignment matrix  1740 . The alignment matrix  1740  can further comprise a plurality of apertures and/or slots, for example, extending therethrough which can be configured to receive the staple legs  1721  therein. In at least one such embodiment, each aperture can be configured to closely receive a staple leg  1721  such that there is little, if any, relative movement between the staple leg  1721  and the sidewalls of the aperture. In certain embodiments, the alignment matrix apertures may not extend entirely through the alignment matrix  1740  and the staple legs  1721  may be required to incise the alignment matrix  1740  as the staple legs  1721  are pushed therethrough. 
     In various embodiments, the alignment matrix  1740  can be comprised of a molded plastic body which, in at least one embodiment, can be stiffer or less compressible than the inner layer  1712  and/or the outer layer  1711 . In at least one such embodiment, the alignment matrix  1740  can be comprised of a plastic material and/or any other suitable material, such as polydioxanone (PDS) and/or polyglycolic acid (PGA), for example. In certain embodiments, the alignment matrix  1740  can be assembled to the inner layer  1712  and the staple legs  1721  can thereafter be inserted through the alignment matrix  1740  and embedded into the inner layer  1712 . In various embodiments, the bottom surface  1742  of the alignment matrix  1740  can comprise one or more grooves, slots, or troughs, for example, which can be configured to at least partially receive the bases  1722  of the staples  1720 . Similar to the above, the outer layer  1711  can then be placed around the subassembly comprising the inner layer  1712 , the alignment matrix  1740 , and the staples  1720 . Alternatively, the outer layer  1711  can be placed around a subassembly comprising the inner layer  1712  and the alignment matrix  1740  wherein the staples  1720  can be thereafter inserted through the outer layer  1711 , the alignment matrix  1740 , and the inner layer  1712 . In any event, as a result of the above, the inner layer  1712 , the alignment matrix  1740 , and/or the outer layer  1711  can be configured to retain the staples  1720  in position until and/or after they are deformed by an anvil as described above. In at least one such embodiment, the alignment matrix  1740  can serve to hold the staples  1720  in place before the staple cartridge  1700  is implanted within a patient and, in addition, secure the tissue along the staple line after the staple cartridge  1700  has been implanted. In at least one embodiment, the staples  1720  may be secured within the alignment matrix  1740  without being embedded in the inner layer  1712  and/or the outer layer  1711 , for example. 
     In various embodiments, referring now to  FIGS. 34-40 , a staple cartridge, such as staple cartridge  1800 , for example, can be assembled by compressing an inner layer  1812 , inserting staples, such as staples  1820 , for example, into the inner layer  1812 , and wrapping the inner layer  1812  with an outer layer  1811 . Referring primarily to  FIG. 34 , a compressible inner layer  1812  is illustrated as comprising a plurality of staple cavities  1815  defined therein, although other embodiments are envisioned in which the inner layer  1812  does not comprise staple cavities, as described above. Referring now to  FIG. 35 , the compressible inner layer  1812  can be positioned intermediate a transfer plate  1850  and a support plate  1860  and compressed between the compression surfaces  1852  and  1862  thereof, respectively. As illustrated in  FIG. 35 , the top and bottom surfaces of the inner layer  1812  can be compressed toward one another and, in response thereto, the inner layer  1812  can bulge outwardly in the lateral directions. In certain embodiments, the inner layer  1812  can be compressed to a height which is approximately one-third of its original height, for example, and can have a height or thickness between approximately 0.06″ and approximately 0.08″ in its compressed state, for example. As also illustrated in  FIG. 35 , the transfer plate  1850  can further comprise a plurality of staples, such as staples  1820 , for example, positioned within a plurality of staple wells  1853 . In addition, the transfer plate  1850  can further comprise a plurality of drivers  1851  which can be configured to push the staples  1820  upwardly and out of the staple wells  1853 . Referring now to  FIG. 36 , the drivers  1851  can be utilized to push the staple legs  1821  of the staples  1820  into and through the compressed inner layer  1812 . In various embodiments, the drivers  1851  can be configured such that the top surfaces thereof are positioned flush, or at least nearly flush, with the compression surface  1852  of the transfer plate  1850  when the staples  1820  have been fully deployed from the staple wells  1853  of transfer plate  1850 . In certain embodiments, as also illustrated in  FIG. 36 , the support plate  1860  can comprise a plurality of receiving apertures  1861  which can be configured to receive the staple legs  1821 , or at least the tips of the staple legs  1821 , after they are pushed through the inner layer  1812 . The receiving apertures  1861 , or the like, may be necessitated in embodiments where the inner layer  1812  has been compressed to a height which is shorter than the height of the staples  1820  and, thus, when the staples  1820  have been fully ejected from the staple wells  1853 , the staple legs  1821  may protrude from the top surface of the compressed inner layer  1812 . In certain other embodiments, the inner layer  1812  may be compressed to a height which is taller than the height of the staples  1820  and, as a result, the receiving apertures  1861  in support plate  1860  may be unnecessary. 
     After the staples  1820  have been inserted into the inner layer  1812 , referring now to  FIG. 37 , the support plate  1860  can be moved away from the transfer plate  1850  in order to allow the inner layer  1812  to decompress. In such circumstances, the inner layer  1812  can resiliently re-expand to its original, or at least near-original, uncompressed height. As the inner layer  1812  re-expands, the height of the inner layer  1812  can increase such that it exceeds the height of the staples  1820  and such that the staple legs  1821  of the staples  1820  no longer protrude from the top surface of the inner layer  1812 . In various circumstances, the receiving apertures  1861  can be configured to hold the staple legs  1821  in position at least until the support plate  1860  has been sufficiently moved away such that the legs  1821  are no longer positioned within the receiving apertures  1861 . In such circumstances, the receiving apertures  1861  can assist in maintaining the relative alignment of the staples  1820  within the inner layer  1812  as it re-expands. In various circumstances, the inner layer  1812  and the staples  1820  positioned therein can comprise a subassembly  1801  which, referring now to  FIG. 38 , can be inserted into an outer layer  1811 , for example. In at least one such embodiment, the outer layer  1811  can comprise a cavity  1802  defined therein which can be configured to receive the subassembly  1801  therein. In various circumstances, a tool, such as pliers  1855 , for example, can be utilized to pull the outer layer  1811  onto the subassembly  1801 . Once the subassembly  1801  has been sufficiently positioned within the outer layer  1811 , referring now to  FIG. 39 , the outer layer  1811  can be sealed. In various embodiments, the outer layer  1811  can be sealed utilizing the application of heat energy to a portion thereof. More particularly, in at least one embodiment, the outer layer  1811  can be comprised of a plastic material wherein the open end of the outer layer  1811  can be heat-staked by one or more heated elements, or irons,  1856  in order to bond and/or seal the perimeter of the open end of the outer layer  1811  together. In at least one such embodiment, referring now to  FIG. 40 , an excess portion  1857  of the outer layer  1811  can be removed and the staple cartridge  1800  can then be used as described herein. 
     As described above, a staple cartridge can be positioned within and/or secured to a staple cartridge attachment portion. In various embodiments, referring now to  FIGS. 41 and 42 , a staple cartridge attachment portion can comprise a staple cartridge channel, such as staple cartridge channel  1930 , for example, which can be configured to receive at least a portion of a staple cartridge, such as staple cartridge  1900 , for example, therein. In at least one embodiment, the staple cartridge channel  1930  can comprise a bottom support surface  1931 , a first lateral support wall  1940 , and a second lateral support wall  1941 . In use, the staple cartridge  1900  can be positioned within the staple cartridge channel  1930  such that the staple cartridge  1900  is positioned against and/or adjacent to the bottom support surface  1931  and positioned intermediate the first lateral support wall  1940  and the second lateral support wall  1941 . In certain embodiments, the first lateral support wall  1940  and the second lateral support wall  1941  can define a lateral gap therebetween. In at least one such embodiment, the staple cartridge  1900  can comprise a lateral width  1903  which is the same as and/or wider than the lateral gap defined between the support walls  1940  and  1941  such that a compressible, implantable cartridge body  1910  of the staple cartridge  1900  can fit securely between the walls  1940  and  1941 . In certain other embodiments, the lateral width  1903  of the staple cartridge  1900  can be shorter than the gap defined between the first and second side walls  1940  and  1941 . In various embodiments, at least a portion of the walls  1940  and  1941  and the bottom support surface  1931  can be defined by a stamped metal channel while, in at least one embodiment, at least a portion of the lateral support wall  1940  and/or lateral support wall  1941  can be comprised of a flexible material, such as an elastomeric material, for example. Referring primarily to  FIG. 41 , the first side wall  1940  and the second side wall  1941  of the staple cartridge channel  1930  can each be comprised of a rigid portion  1933  extending upwardly from the bottom support surface  1931  and a flexible portion  1934  extending upwardly from the rigid portions  1933 . 
     In various embodiments, further to the above, the cartridge body  1910  of staple cartridge  1900  can be comprised of one or more compressible layers, such as first layer  1911  and second layer  1912 , for example. When the cartridge body  1910  is compressed against the bottom support surface  1931  by an anvil, as described above, the side portions of the cartridge body  1910  can expand laterally. In embodiments where the staple cartridge  1930  is comprised of rigid side walls, the lateral expansion of the cartridge body  1910  can be prevented, or at least limited, by the rigid side walls and, as a result, a significant amount of internal pressure, or stress, can be developed within the cartridge body  1910 . In embodiments where at least a portion of the staple cartridge  1930  is comprised of flexible side walls, the flexible side walls can be configured to flex laterally and permit the side portions of the cartridge body  1910  to expand laterally, thereby reducing the internal pressure, or stress, generated within the cartridge body  1910 . In embodiments where the cartridge channel does not comprise lateral side walls, or comprises lateral sidewalls which are relatively shorter than the staple cartridge, the side portions of the staple cartridge may expand laterally uninhibited, or at least substantially uninhibited. In any event, referring now to  FIG. 42 , a staple cartridge channel  2030  can comprise lateral sidewalls  2040  and  2041  which can be entirely comprised of a flexible material, such as an elastomeric material, for example. The staple cartridge channel  2030  can further comprise lateral slots  2033  extending along the sides of the bottom support surface  2031  of the staple cartridge channel  2030  which can be configured to receive and secure at least a portion of the lateral sidewalls  2040  and  2041  therein. In certain embodiments, the lateral side walls  2040  and  2041  can be secured in the slots  2033  via a snap-fit and/or press-fit arrangement while, in at least some embodiments, the lateral side walls  2040  and  2041  can be secured in the slots  2033  by one or more adhesives. In at least one embodiment, the sidewalls  2040  and  2041  may be detachable from the bottom support surface  2031  during use. In any event, a compressible, implantable cartridge body  2010  can be detached and/or disengaged from the lateral side walls  2040  and  2041  when the cartridge body  2010  is implanted with the staples  2020 . 
     In various embodiments, referring now to  FIG. 43 , a surgical instrument can comprise a shaft  2150  and an end effector extending from the distal end of the shaft  2150 . The end effector can comprise, similar to the above, a staple cartridge channel  2130 , an anvil  2140  movable between an open position and a closed position, and a staple cartridge  2100  positioned intermediate the staple cartridge channel  2130  and the anvil  2140 . Also similar to the above, the staple cartridge  2100  can comprise a compressible, implantable cartridge body  2110  and a plurality of staples  2120  positioned in the cartridge body  2110 . In various embodiments, the staple cartridge channel  2130  can comprise, one, a bottom support surface  2131  against which the staple cartridge  2100  can be positioned, two, a distal end  2135  and, three, a proximal end  2136 . In at least one embodiment, as illustrated in  FIG. 43 , the staple cartridge  2100  can comprise a first end  2105  which can be positionable in the distal end  2135  of the staple cartridge channel  2130  and a second end  2106  which can be positionable in the proximal end  2136  of the staple cartridge channel  2130 . In various embodiments, the distal end  2135  of the staple cartridge channel  2130  can comprise at least one distal retention feature, such as a retention wall  2137 , for example, and, similarly, the proximal end  2136  can comprise at least one proximal retention feature, such as a retention wall  2138 , for example. In at least one such embodiment, the distal retention wall  2137  and the proximal retention wall  2138  can define a gap therebetween which can be equal to or less than the length of the staple cartridge  2100  such that the staple cartridge  2100  can fit securely within the staple cartridge channel  2130  when the staple cartridge  2100  is inserted therein. 
     In various embodiments, referring again to  FIGS. 23 and 24 , a staple cartridge, such as staple cartridge  1200 , for example, can comprise a flat, or at least substantially flat, tissue-contacting surface  1219 . In at least one such embodiment, the staple cartridge body  1210  of staple cartridge  1200  can comprise a first end  1205  which can be defined by a first height, or thickness,  1207  and a second end  1206  which can be defined by a second height, or thickness,  1208 , wherein the first height  1207  can be equal to, or at least substantially equal to, the second height  1208 . In certain embodiments, the cartridge body  1210  can comprise a constant, or at least substantially constant, height, or thickness, between the first end  1205  and the second end  1206 . In at least one such embodiment, the tissue-contacting surface  1219  can be parallel, or at least substantially parallel, to the bottom surface  1218  of the cartridge body  1210 . In various embodiments, referring once again to  FIG. 43 , the first end  2105  of the cartridge body  2110  of staple cartridge  2100  can be defined by a first height  2107  which is different than a second height  2108  of the second end  2106 . In the illustrated embodiment, the first height  2107  is larger than the second height  2108 , although the second height  2108  could be larger than the first height  2107  in alternative embodiments. In various embodiments, the height of the cartridge body  2110  can decrease linearly and/or geometrically between the first end  2105  and the second end  2106 . In at least one such embodiment, the tissue-contacting surface  2119 , which extends between the first end  2105  and the second end  2106 , can be oriented along an angle defined therebetween. In at least one such embodiment, the tissue-contacting surface  2119  may not be parallel to the bottom surface  2118  of the cartridge body  2110  and/or parallel to the support surface  2131  of the staple cartridge channel  2130 . 
     In various embodiments, referring again to  FIGS. 43 and 44 , the anvil  2140  can comprise a tissue-contacting surface  2141  which can be parallel, or at least substantially parallel, to the support surface  2131  of the staple cartridge channel  2130  when the anvil  2140  is in a closed position, as illustrated in  FIG. 44 . When the anvil  2140  is in a closed position, the anvil  2140  can be configured to compress the first end  2105  of the staple cartridge  2100  more than the second end  2106  owing to the taller height of the first end  2105  and the shorter height of the second end  2106 . In some circumstances, including circumstances where the tissue T positioned intermediate the tissue contacting surfaces  2119  and  2141  has a constant, or at least substantially constant, thickness, the pressure generated within the tissue T and the cartridge  2100  can be greater at the distal end of the end effector than the proximal end of the end effector. More particularly, when the tissue T between the anvil  2140  and the staple cartridge  2100  has a substantially constant thickness, the tissue T positioned intermediate the distal end  2145  of the anvil  2140  and the first end  2105  of the staple cartridge  2100  can be more compressed than the tissue T positioned intermediate the proximal end  2146  of the anvil  2140  and the second end  2106  of the staple cartridge  2100 . In various embodiments, a pressure gradient can be generated within the tissue T between the proximal end and the distal end of the end effector. More particularly, in at least one embodiment, when the tissue T between the anvil  2140  and the staple cartridge  2100  has a substantially constant thickness and the height of the staple cartridge  2100  decreases linearly from the distal end to the proximal end of the end effector, the pressure within the tissue T can decrease linearly from the distal end of the end effector to the proximal end of the end effector. Similarly, in at least one embodiment, when the tissue T between the anvil  2140  and the staple cartridge  2100  has a substantially constant thickness and the height of the staple cartridge  2100  decreases geometrically from the distal end to the proximal end of the end effector, the pressure within the tissue T can decrease geometrically from the distal end of the end effector to the proximal end of the end effector. 
     In various embodiments, referring again to  FIG. 43 , the tissue T positioned intermediate the staple cartridge  2100  and the anvil  2140  may not have a constant thickness throughout. In at least one such circumstance, the tissue T positioned between the proximal end  2146  of the anvil  2140  and the second end  2106  of the staple cartridge  2100  may be thicker than the tissue T positioned between the distal end  2145  of the anvil  2140  and the first end  2105  of the staple cartridge  2100 . In such circumstances, as a result, the thicker tissue T may be generally positioned above the shorter proximal end  2106  of the staple cartridge  2100  and the thinner tissue T may be generally positioned above the taller distal end  2105 . In use, the firing collar  2152  of the shaft  2150  can be advanced distally along the shaft spine  2151  such that the firing collar  2152  engages the cam portion  2143  of the anvil  2140  and rotates the anvil  2140  toward the staple cartridge  2100  as illustrated in  FIG. 44 . Once the anvil  2140  has been rotated into a fully-closed position, the tissue T may be compressed between the tissue-contacting surfaces  2119  and  2141  and, even though the height of the staple cartridge  2100  may not be constant between the proximal and distal ends of the end effector, the pressure or compressive forces applied to the tissue T may be constant, or at least substantially constant, thereacross. More particularly, as the thinner tissue T may be associated with the taller height of the staple cartridge  2100  and the thicker tissue T may be associated with the shorter height of the staple cartridge  2100 , the cumulative, or summed, height of the tissue T and the staple cartridge  2100  may be constant, or at least substantially constant, between the proximal and distal ends of the end effector and, as a result, the compression of this cumulative height by the anvil  2140  may be constant, or at least substantially constant, thereacross. 
     In various embodiments, referring again to  FIGS. 43 and 44 , the staple cartridge  2100  can comprise an asymmetrical configuration. In at least one such embodiment, for example, the height of the staple cartridge  2100  at the first end  2105  thereof may be higher than the height of the staple cartridge  2100  at the second end  2106  thereof. In certain embodiments, the staple cartridge  2100  and/or the staple cartridge channel  2130  can comprise one or more alignment and/or retention features which can be configured to assure that the staple cartridge  2100  can only be positioned within the staple cartridge channel  2130  in one orientation, i.e., an orientation in which the first end  2105  is positioned in the distal end  2135  of the staple cartridge channel  2130  and the second end  2106  is positioned in the proximal end  2136 . In various alternative embodiments, the staple cartridge  2100  and/or the staple cartridge channel  2130  can comprise one or more alignment and/or retention features which can be configured to permit the staple cartridge  2100  to be positioned within the staple cartridge channel  2130  in more than one orientation. Referring now to  FIG. 45 , for example, the staple cartridge  2100  can be positioned within the staple cartridge channel  2130  such that the first end  2105  of the staple cartridge  2100  can be positioned in the proximal end  2136  of the staple cartridge channel  2130  and the second end  2106  can be positioned in the distal end  2135 . In various embodiments, as a result, the shorter height of the staple cartridge  2100  can be positioned proximate the distal retention wall  2137  and the taller height of the staple cartridge  2100  can be positioned proximate to the proximal retention wall  2138 . In at least one such embodiment, the staple cartridge  2100  can be suitably arranged to apply a constant, or at least substantially constant, clamping pressure to tissue T having a thicker portion within the distal end of the end effector and a thinner portion within the proximal end of the end effector. In various embodiments, the staple cartridge  2100 , for example, can be selectively oriented within the staple cartridge channel  2130 . In at least one such embodiment, the alignment and/or retention features of the staple cartridge  2100  can be symmetrical and a surgeon can selectively orient the staple cartridge  2100  within the staple cartridge channel  2130  in the orientations depicted in  FIG. 43  and  FIG. 45 , for example. 
     Further to the above, the implantable cartridge body  2110  can comprise a longitudinal axis  2109  which, when the staple cartridge  2100  is positioned in the staple cartridge channel  2130 , can extend between the proximal and distal ends of the end effector. In various embodiments, the thickness of the cartridge body  2110  can generally decrease and/or generally increase between the first end  2105  and the second end  2106  along the longitudinal axis  2109 . In at least one such embodiment, the distance, or height, between the bottom surface  2118  and the tissue-contacting surface  2119  can generally decrease and/or generally increase between the first end  2105  and the second end  2106 . In certain embodiments, the thickness of the cartridge body  2110  can both increase and decrease along the longitudinal axis  2109 . In at least one such embodiment, the thickness of the cartridge body  2110  can comprise one or more portions which increase in thickness and one or more portions which can decrease in thickness. In various embodiments, the staple cartridge  2100  can comprise a plurality of staples  2120  positioned therein. In use, as described above, the staples  2120  can be deformed when the anvil  2140  is moved into a closed position. In certain embodiments, each staple  2120  can have the same, or at least substantially the same, height. In at least one such embodiment, the height of a staple can be measured from the bottom of the base of the staple to the top, or tip, of the tallest leg of the staple, for example. 
     In various embodiments, the staples within a staple cartridge can have different staple heights. In at least one such embodiment, a staple cartridge can comprise a first group of staples having a first staple height which are positioned in a first portion of a compressible cartridge body and a second group of staples having a second staple height which are positioned in a second portion of the compressible cartridge body. In at least one embodiment, the first staple height can be taller than the second staple height and the first group of staples can be positioned in the first end  2105  of the staple cartridge  2100  while the second group of staples can be positioned in the second end  2106 . Alternatively, the taller first group of staples can be positioned in the second end  2106  of the staple cartridge  2100  while the shorter second group of staples can be positioned in the first end  2105 . In certain embodiments, a plurality of staple groups, each group having a different staple height, can be utilized. In at least one such embodiment, a third group having an intermediate staple height can be positioned in the cartridge body  2110  intermediate the first group of staples and the second group of staples. In various embodiments, each staple within a staple row in the staple cartridge can comprise a different staple height. In at least one embodiment, the tallest staple within a staple row can be positioned on a first end of a staple row and the shortest staple can be positioned on an opposite end of the staple row. In at least one such embodiment, the staples positioned intermediate the tallest staple and the shortest staple can be arranged such that the staple heights descend between the tallest staple and the shortest staple, for example. 
     In various embodiments, referring now to  FIG. 46 , an end effector of a surgical stapler can comprise an anvil  2240 , a staple cartridge channel  2230 , and a staple cartridge  2200  supported by the staple cartridge channel  2230 . The staple cartridge  2200  can comprise a compressible, implantable cartridge body  2210  and a plurality of staples, such as staples  2220   a  and staples  2220   b , for example, positioned therein. In various embodiments, the staple cartridge channel  2230  can comprise a cartridge support surface  2231  and a plurality of staple support slots, such as support slots  2232   a  and  2232   b , for example, defined therein. In at least one such embodiment, the staple cartridge  2200  can comprise two outer rows of staples  2220   a  and two inner rows of staples  2220   b , wherein the support slots  2232   a  can be configured to support the staples  2220   a  and the support slots  2232   b  can be configured to support the staples  2220   b . Referring to  FIGS. 46 and 47 , the anvil  2240  can comprise a plurality of staple forming pockets  2242  defined therein which can be configured to receive and deform the staples  2220   a  and  2220   b  when the anvil  2240  is moved toward the staple cartridge  2200 . In at least one such embodiment, the bottom surfaces of the support slots  2232   a  can be a first distance  2201   a  away from the top surfaces of the staple forming pockets  2242  while the bottom surfaces of the support slots  2232   b  can be a second distance  2201   b  away from the top surfaces of the staple forming pockets  2242 . In at least one such embodiment, the support slots  2232   b  are positioned closer to the anvil  2240  owing to the raised step in the support surface  2231  in which they are defined. Owing to the different distances  2201   a  and  2201   b , in various embodiments, the outer rows of staples  2220   a  and the inner rows of staples  2220   b  can be deformed to different formed heights. In various circumstances, staples deformed to different formed heights can apply different clamping pressures or forces to the tissue T being stapled. In addition to the above, the staples can begin with different unformed staple heights. In at least one such embodiment, referring again to  FIG. 46 , the outer staples  2220   a  can have an initial, unformed height which is greater than the initial, unformed height of the inner staples  2220   b . As illustrated in  FIGS. 46 and 47 , the inner staples  2220   b , which have a shorter unformed height than the outer staples  2220   a , can also have a shorter formed height than the outer staples  2220   b . In various alternative embodiments, the inner staples  2220   b  may have a taller unformed height than the outer staples  2220   a  yet have a shorter deformed staple height than the outer staples  2220   a.    
     In various embodiments, further to the above, the anvil  2240  can be moved into a closed position, as illustrated in  FIG. 47 , in order to compress the cartridge body  2210  and deform the staples  2220   a  and  2220   b . In certain embodiments, a surgical stapler comprising the end effector depicted in  FIGS. 46 and 47 , for example, can further comprise a cutting member which can be configured to transect the tissue T positioned intermediate the anvil  2240  and the staple cartridge  2200 . In at least one such embodiment, the anvil  2240 , the staple cartridge channel  2230  and/or the staple cartridge  2200  can define a slot configured to slidably receive a cutting member therein. More particularly, the anvil  2240  can comprise a slot portion  2249 , the staple cartridge channel  2230  can comprise a slot portion  2239 , and the staple cartridge  2200  can comprise a slot portion  2203  which can be aligned, or at least substantially aligned, with one another when the anvil  2240  is in a closed, or at least substantially closed, position. In various embodiments, the cutting member can be moved from the proximal end of the end effector toward the distal end of the end effector after the anvil  2240  has been closed and the staples  2220   a ,  2220   b  have been deformed. In at least one embodiment, the cutting member can be moved independently of the staple deformation process. In certain embodiments, the cutting member can be advanced at the same time that the staples are being deformed. In any event, in at least one embodiment, the cutting member can be configured to incise the tissue along a path positioned intermediate the inner rows of staples  2220   b.    
     In various embodiments, as illustrated in  FIG. 47 , the inner staples  2220   b  can be formed to a shorter height than the outer staples  2220   a  wherein the inner staples  2220   b  can apply a larger clamping pressure or force to the tissue adjacent to the cut line created by the cutting member. In at least one such embodiment, the larger clamping pressure or force created by the inner staples  2220   b  can provide various therapeutic benefits such as reducing bleeding from the incised tissue T while the smaller clamping pressure created by the outer staples  2220   a  can provide flexibility within the stapled tissue. In various embodiments, referring again to  FIGS. 46 and 47 , the anvil  2240  can further comprise at least one piece of buttress material, such as buttress material  2260 , for example, attached thereto. In at least one such embodiment, the legs of the staples  2220   a ,  2220   b  can be configured to incise the buttress material  2260  and/or pass through apertures in the buttress material  2260  when the staple cartridge  2200  is compressed by the anvil  2240  and thereafter contact the staple forming pockets  2242  in the anvil  2240 . As the legs of the staples  2220   a ,  2220   b  are being deformed, the legs can contact and/or incise the buttress material  2260  once again. In various embodiments, the buttress material  2260  can improve the hemostasis of and/or provide strength to the tissue being stapled. 
     In various embodiments, referring again to  FIGS. 46 and 47 , the bottom surface of the cartridge body  2210  can comprise a stepped contour which matches, or at least substantially matches, the stepped contour of the cartridge support surface  2231 . In certain embodiments, the bottom surface of the cartridge body  2210  can deform to match, or at least substantially match, the contour of the cartridge support surface  2231 . In various embodiments, referring now to  FIG. 48 , an end effector, similar to the end effector depicted in  FIG. 46 , for example, can comprise a staple cartridge  2300  positioned therein. The staple cartridge  2300  can comprise a compressible, implantable body  2310  comprising an inner layer  2312  and an outer layer  2311  wherein, further to the above, the outer layer  2311  can be comprised of a water impermeable material in at least one embodiment. In various embodiments, the outer layer  2311  can extend around the staples  2220   a ,  2220   b  and can be positioned intermediate the staples  2220   a ,  2220   b  and the support slots  2232   a ,  2232   b , respectively. In various embodiments, referring now to  FIG. 49 , an end effector, similar to the end effector depicted in  FIG. 46 , for example, can comprise a staple cartridge  2400  positioned therein. Similar to the staple cartridge  2300 , the compressible, implantable cartridge body  2410  of staple cartridge  2400  can comprise an inner layer  2412  and an outer layer  2411 ; however; in at least one embodiment, the cartridge body  2410  may not comprise a cutting member slot therein. In at least one such embodiment, the cutting member may be required to incise the inner layer  2412  and/or the outer layer  2411 , for example, as it is advanced through the staple cartridge. 
     In various embodiments, referring now to  FIG. 50 , an end effector of a surgical stapler can comprise an anvil  2540 , a staple cartridge channel  2530 , and a staple cartridge  2500  positioned in the staple cartridge channel  2530 . Similar to the above, the staple cartridge  2500  can comprise a compressible, implantable cartridge body  2510 , outer rows of staples  2220   a , and inner rows of staples  2220   b . The staple cartridge channel  2530  can comprise a flat, or an at least substantially flat, cartridge support surface  2531  and staple support slots  2532  defined therein. The anvil  2540  can comprise a stepped surface  2541  and a plurality of staple forming pockets, such as forming pockets  2542   a  and  2542   b , for example, defined therein. Similar to the above, the forming pockets  2542   a  and the support slots  2532  can define a distance therebetween which is greater than the distance between the forming pockets  2452   b  and the support slots  2532 . In various embodiments, the anvil  2540  can further comprise a piece of buttress material  2560  attached to the stepped surface  2541  of the anvil  2540 . In at least one such embodiment, the buttress material  2560  can conform, or at least substantially conform, to the stepped surface  2541 . In various embodiments, the buttress material  2560  can be removably attached to the surface  2541  by at least one adhesive, such as fibrin and/or protein hydrogel, for example. In certain embodiments, the cartridge body  2510  can also comprise a stepped profile which, in at least one embodiment, parallels, or at least substantially parallels, the stepped surface  2541  of the anvil  2540 . More particularly, in at least one embodiment, the anvil  2540  can comprise steps  2548  extending toward the staple cartridge  2500  wherein the steps  2548  can comprise a step height which equals, or at least substantially equals, the step height of the steps  2508  extending from the cartridge body  2510 . In at least one such embodiment, as a result of the above, the amount of the compressible cartridge body  2510  that can be captured in the first staples  2220   a  can be different than the amount of the compressible cartridge body  2510  that can be captured in the second staples  2220   b , for example. 
     In various embodiments, referring now to  FIG. 51 , an end effector can comprise an anvil  2640 , a staple cartridge channel  2530 , and a staple cartridge  2600  positioned therebetween. The staple cartridge  2600  can comprise a compressible, implantable cartridge body  2610  including an inner layer  2612 , an outer layer  2611 , and a plurality of staples, such as staples  2220   a  and  2200   b , for example, positioned therein. In various embodiments, the anvil  2640  can comprise a plurality of staple forming pockets  2642  in surface  2641  and the staple cartridge channel  2530  can comprise a plurality of staple forming slots  2532  defined in the support surface  2531 . As illustrated in  FIG. 51 , the anvil surface  2641  can be parallel, or at least substantially parallel, to the cartridge support surface  2531  wherein each forming pocket  2642  can be positioned an equal, or at least substantially equal, distance away from an opposing and corresponding staple support slot  2532 . In various embodiments, the staple cartridge  2600  can comprise staples having the same, or at least substantially the same, initial, unformed staple height and, in addition, the same, or at least substantially the same, formed staple height. In certain other embodiments, the outer rows of staples can comprise staples  2220   a  and the inner rows of staples can comprise staples  2220   b  wherein, as discussed above, the staples  2220   a  and  2220   b  can have different unformed staple heights. When the anvil  2640  is moved toward the staple cartridge  2600  into a closed position, the staples  2220   a  and  2220   b  can be formed such that they have the same, or at least substantially the same, formed staple height. In at least one such embodiment, as a result of the above, the formed outer staples  2220   a  and the inner staples  2220   b  may have the same, or at least substantially the same, amount of compressible cartridge body  2610  contained therein; however, as the outer staples  2220   a  have a taller unformed staple height than the inner staples  2220   b  and may have the same formed staple height nonetheless, a greater clamping pressure can be generated in the outer staples  2220   a  than the inner staples  2220   b , for example. 
     In various embodiments, referring now to  FIG. 52 , an end effector of a surgical stapler can comprise an anvil  2740 , a staple cartridge channel  2530 , and a staple cartridge  2700  positioned within the staple cartridge channel  2530 . Similar to the above, the staple cartridge  2700  can comprise a compressible, implantable cartridge body  2710  comprising an inner layer  2712 , an outer layer  2711 , and a plurality of staples, such as staples  2220   a  and  2220   b , for example, positioned therein. In at least one embodiment, the thickness of the cartridge body  2710  can vary across its width. In at least one such embodiment, the cartridge body  2710  can comprise a center portion  2708  and side portions  2709 , wherein the center portion  2708  can comprise a thickness which is greater than the thickness of the side portions  2709 . In various embodiments, the thickest portion of the cartridge body  2710  can be located at the center portion  2708  while the thinnest portion of the cartridge body  2710  can be located at the side portions  2709 . In at least one such embodiment, the thickness of the cartridge body  2710  can decrease gradually between the center portion  2708  and the side portions  2709 . In certain embodiments, the thickness of the cartridge body  2710  can decrease linearly and/or geometrically between the center portion  2708  and the side portions  2709 . In at least one such embodiment, the tissue-contacting surface  2719  of cartridge body  2710  can comprise two inclined, or angled, surfaces which slope downwardly from the center portion  2708  toward the side portions  2709 . In various embodiments, the anvil  2740  can comprise two inclined, or angled, surfaces which parallel, or at least substantially parallel, the inclined tissue-contacting surfaces  2719 . In at least one embodiment, the anvil  2740  can further comprise at least one piece of buttress material  2760  attached to the inclined surfaces of the anvil  2740 . 
     In various embodiments, further to the above, the inner rows of staples in the staple cartridge  2700  can comprise the taller staples  2220   a  and the outer rows of staples can comprise the shorter staples  2220   b . In at least one embodiment, the taller staples  2220   a  can be positioned within and/or adjacent to the thicker center portion  2708  while the staples  2220   b  can be positioned within and/or adjacent to the side portions  2709 . In at least one such embodiment, as a result of the above, the taller staples  2220   a  can capture more material of the implantable cartridge body  2710  than the shorter staples  2220   b . Such circumstances could result in the staples  2220   a  applying a greater clamping pressure to the tissue T than the staples  2220   b . In certain embodiments, even though the taller staples  2220   a  may capture more material of the cartridge body  2710  therein than the shorter staples  2220   b , the taller staples  2220   a  may have a taller formed staple height than the shorter staples  2220   b  owing to the inclined arrangement of the staple forming pockets  2742   a  and  2742   b . Such considerations can be utilized to achieve a desired clamping pressure within the tissue captured by the staples  2220   a  and  2220   b  wherein, as a result, the clamping pressure in the staples  2220   a  can be greater than, less than, or equal to the clamping pressure applied to the tissue by the staples  2220   b , for example. In various alternative embodiments to the end effector illustrated in  FIG. 52 , the shorter staples  2220   b  can be positioned within and/or adjacent to the thicker center portion  2708  of the cartridge body  2710  and the taller staples  2220   a  can be positioned within and/or adjacent to the thinner side portions  2709 . Furthermore, although the staple cartridge  2700  is depicted as comprising inner and outer rows of staples, the staple cartridge  2700  may comprise additional rows of staples, such as staple rows positioned intermediate the inner and outer rows of staples, for example. In at least one such embodiment, the intermediate staple rows can comprise staples having an unformed staple height which is intermediate the unformed staple heights of the staples  2220   a  and  2220   b  and a formed staple height which is intermediate the formed staple heights of the staples  2220   a  and  2220   b , for example. 
     In various embodiments, referring now to  FIG. 53 , an end effector of a surgical stapler can comprise an anvil  2840 , a staple cartridge channel  2530 , and a staple cartridge  2800  positioned within the staple cartridge channel  2530 . Similar to the above, the staple cartridge  2800  can comprise a compressible, implantable cartridge body  2810  comprising an inner layer  2812 , an outer layer  2811 , and a plurality of staples, such as staples  2220   a  and  2220   b , for example, positioned therein. In at least one embodiment, the thickness of the cartridge body  2810  can vary across its width. In at least one such embodiment, the cartridge body  2810  can comprise a center portion  2808  and side portions  2809 , wherein the center portion  2808  can comprise a thickness which is less than the thickness of the side portions  2809 . In various embodiments, the thinnest portion of the cartridge body  2810  can be located at the center portion  2808  while the thickest portion of the cartridge body  2810  can be located at the side portions  2809 . In at least one such embodiment, the thickness of the cartridge body  2810  can increase gradually between the center portion  2808  and the side portions  2809 . In certain embodiments, the thickness of the cartridge body  2810  can increase linearly and/or geometrically between the center portion  2808  and the side portions  2809 . In at least one such embodiment, the tissue-contacting surface  2819  of cartridge body  2810  can comprise two inclined, or angled, surfaces which slope upwardly from the center portion  2808  toward the side portions  2809 . In various embodiments, the anvil  2840  can comprise two inclined, or angled, surfaces which parallel, or at least substantially parallel, the inclined tissue-contacting surfaces  2819 . In at least one embodiment, the anvil  2840  can further comprise at least one piece of buttress material  2860  attached to the inclined surfaces of the anvil  2840 . In various embodiments, further to the above, the outer rows of staples in the staple cartridge  2800  can comprise the taller staples  2220   a  and the inner rows of staples can comprise the shorter staples  2220   b . In at least one embodiment, the taller staples  2220   a  can be positioned within and/or adjacent to the thicker side portions  2809  while the staples  2220   b  can be positioned within and/or adjacent to the center portion  2808 . In at least one such embodiment, as a result of the above, the taller staples  2220   a  can capture more material of the implantable cartridge body  2810  than the shorter staples  2220   b.    
     As described above with regard to the embodiment of  FIG. 46 , for example, the staple cartridge channel  2230  can comprise a stepped support surface  2231  which can be configured to support the staples  2220   a  and  2220   b  at different heights with respect the anvil  2240 . In various embodiments, the staple cartridge channel  2230  can be comprised of metal and the steps in the support surface  2231  may be formed in the support surface  2231  by a grinding operation, for example. In various embodiments, referring now to  FIG. 54 , an end effector of a surgical instrument can comprise a staple cartridge channel  2930  comprising a support insert  2935  positioned therein. More particularly, in at least one embodiment, the staple cartridge channel  2930  can be formed such that it has a flat, or at least substantially flat, support surface  2931 , for example, which can be configured to support the insert  2935  which comprises the stepped surfaces for supporting the staples  2220   a  and  2220   b  of the staple cartridge  2200  at different heights. In at least one such embodiment, the insert  2935  can comprise a flat, or at least substantially flat, bottom surface which can be positioned against the support surface  2931 . The insert  2935  can further comprise support slots, grooves, or troughs  2932   a  and  2932   b  which can be configured to support the staples  2220   a  and  2220   b , respectively, at different heights. Similar to the above, the insert  2935  can comprise a knife slot  2939  defined therein which can be configured to permit a cutting member to pass therethrough. In various embodiments, the staple cartridge channel  2930  can be comprised of the same material as or a different material than the support insert  2935 . In at least one embodiment, the staple cartridge channel  2930  and the support insert  2935  can both be comprised of metal, for example, while, in other embodiments, the staple cartridge channel  2930  can be comprised of metal, for example, and the support insert  2935  can be comprised of plastic, for example. In various embodiments, the support insert  2935  can be fastened and/or welded into the staple cartridge channel  2930 . In certain embodiments, the support insert  2935  can be snap-fit and/or press-fit into the staple cartridge channel  2930 . In at least one embodiment the support insert  2935  can be secured in the staple cartridge channel  2930  using an adhesive. 
     In various embodiments, referring now to  FIG. 55 , an end effector of a surgical stapler can comprise an anvil  3040 , a staple cartridge channel  3030 , and a compressible, implantable staple cartridge  3000  positioned in the staple cartridge channel  3030 . Similar to the above, the anvil  3040  can comprise a plurality of staple-forming pockets  3042  defined therein and a knife slot  3049  which can be configured to slidably receive a cutting member therein. Also similar to the above, the staple cartridge channel  3030  can comprise a plurality of staple support slots  3032  defined therein and a knife slot  3039  which can also be configured to slidably receive a cutting member therein. In various embodiments, the staple cartridge  3000  can comprise a first layer  3011 , a second layer  3012 , and a plurality of staples, such as staples  3020   a  and  3020   b , for example, positioned therein. In at least one embodiment, the staples  3020   a  can comprise an unformed staple height which is taller than the unformed staple height of the staples  3020   b . In various embodiments, the first layer  3011  can be comprised of a first compressible material and the second layer  3012  can be comprised of a second compressible material. In certain embodiments, the first compressible material can be compressed at a rate which is higher than the second compressible material while, in certain other embodiments, the first compressible material can be compressed at a rate which is lower than the second compressible material. In at least one embodiment, the first compressible material can be comprised of a resilient material which can comprise a first spring rate and the second compressible material can be comprised of a resilient material which can comprise a second spring rate which is different than the first spring rate. In various embodiments, the first compressible material can comprise a spring rate which is greater than the spring rate of the second compressible material. In certain other embodiments, the first compressible material can comprise a spring rate which is less than the spring rate of the second compressible material. In various embodiments, the first compressible layer can comprise a first stiffness and the second compressible layer can comprise a second stiffness, wherein the first stiffness is different than the second stiffness. In various embodiments, the first compressible layer can comprise a stiffness which is greater than the stiffness of the second compressible layer. In certain other embodiments, the first compressible layer can comprise a stiffness which is less than the stiffness of the second compressible layer. 
     In various embodiments, referring again to  FIG. 55 , the second layer  3012  of the staple cartridge  3000  can comprise a constant, or at least substantially constant, thickness across the width thereof. In at least one embodiment, the first layer  3011  can comprise a thickness which varies across the width thereof. In at least one such embodiment, the first layer  3011  can comprise one or more steps  3008  which can increase the thickness of the cartridge body  3010  in certain portions of the cartridge body  3010 , such as the center portion, for example. Referring again to  FIG. 55 , the shorter staples  3020   b  can be positioned in or aligned with the steps  3008 , i.e., the thicker portions of the cartridge body  3010 , and the taller staples  3020   a  can be positioned in or aligned with the thinner portions of the cartridge body  3010 . In various embodiments, as a result of the thicker and thinner portions of the cartridge body  3010 , the stiffness of the cartridge body  3010  can be greater along the inner rows of staples  3020   b  than the outer rows of staples  3020   a . In various embodiments, the first layer  3011  can be connected to the second layer  3012 . In at least one such embodiment, the first layer  3011  and the second layer  3012  can comprise interlocking features which can retain the layers  3011  and  3012  together. In certain embodiments, the first layer  3011  can comprise a first laminate and the second layer  3012  can comprise a second laminate, wherein the first laminate can be adhered to the second laminate by one or more adhesives. In various embodiments, the staple cartridge  3000  can comprise a knife slot  3003  which can be configured to slidably receive a cutting member therein. 
     In various embodiments, referring now to  FIG. 56 , a staple cartridge  3100  can comprise a compressible, implantable cartridge body  3110  comprising a single layer of compressible material and, in addition, a plurality of staples, such as staples  3020   b , for example, positioned therein. In at least one embodiment, the thickness of the cartridge body  3110  can vary across the width thereof. In at least one such embodiment, the cartridge body  3110  can comprise steps  3108  extending along the side portions thereof. In various embodiments, referring now to  FIG. 57 , a staple cartridge  3200  can comprise a compressible, implantable cartridge body  3210  comprising a single layer of compressible material and, in addition, a plurality of staples, such as staples  3020   b , for example, positioned therein. In at least one embodiment, the thickness of the cartridge body  3210  can vary across the width thereof. In at least one such embodiment, the cartridge body  3210  can comprise steps  3208  extending along the center portion thereof. In various embodiments, referring now to  FIG. 58 , a staple cartridge  3300  can comprise a compressible, implantable cartridge body  3310  wherein, similar to the above, the thickness of the cartridge body  3310  can vary across the width thereof. In at least one embodiment, the thickness of the cartridge body  3310  can increase geometrically between the side portions and the center portion of the cartridge body  3310 . In at least one such embodiment, the thickness of the cartridge body  3310  can be defined by an arcuate or curved profile and can comprise an arcuate or curved tissue-contacting surface  3319 . In certain embodiments, the thickness of the cartridge body  3310 , and the contour of the tissue-contacting surface  3319 , can be defined by one radius of curvature or, alternatively, by several radiuses of curvature, for example. In various embodiments, referring now to  FIG. 59 , a staple cartridge  3400  can comprise a compressible, implantable cartridge body  3410  wherein the thickness of the cartridge body  3410  can increase linearly, or at least substantially linearly, between the side portions and the center portion of the cartridge body  3410 . 
     In various embodiments, referring now to  FIG. 60 , a staple cartridge  3500  can comprise a compressible, implantable cartridge body  3510  and a plurality of staples  3520  positioned therein. The implantable cartridge body  3510  can comprise a first inner layer  3512 , a second inner layer  3513 , and an outer layer  3511 . In at least one embodiment, the first inner layer  3512  can comprise a first thickness and the second inner layer  3513  can comprise a second thickness wherein the second inner layer  3513  can be thicker than the first inner layer  3512 . In at least one alternative embodiment, the first inner layer  3512  can be thicker than the second inner layer  3513 . In another alternative embodiment, the first inner layer  3512  can have the same, or at least substantially the same, thickness as the second inner layer  3513 . In certain embodiments, each staple  3520  can comprise a base  3522  and one or more deformable legs  3521  extending from the base  3522 . In various embodiments, each leg  3521  can comprise a tip  3523  which is embedded in the first inner layer  3511  and, in addition, each base  3522  of the staples  3520  can be embedded in the second inner layer  3512 . In at least one embodiment, the first inner layer  3512  and/or the second inner layer  3513  can comprise at least one medicament stored therein and, in various embodiments, the outer layer  3511  can encapsulate and seal the first inner layer  3512  and the second inner layer  3513  such that the medicament does not flow out of the staple cartridge body  3510  until after the outer layer  3511  has been punctured by the staples  3520 . More particularly, further to the above, an anvil can be pushed downwardly against tissue positioned against the tissue-contacting surface  3519  of staple cartridge  3500  such that the cartridge body  3510  is compressed and the surface  3519  is moved downwardly toward, and at least partially below, the staple tips  3523  such that the tips  3523  rupture or puncture the outer layer  3511 . After the outer layer  3511  has been breached by the staple legs  3521 , the at least one medicament M can flow out of the cartridge body  3510  around the staple legs  3521 . In various circumstances, additional compression of the cartridge body  3510  can squeeze additional medicament M out of the cartridge body  3510  as illustrated in  FIG. 61 . 
     In various embodiments, referring again to  FIG. 60 , the outer layer  3511  can comprise a water impermeable, or at least substantially impermeable, wrap which can configured to, one, keep the medicament from prematurely flowing out of the staple cartridge  3500  and, two, prevent fluids within a surgical site, for example, from prematurely entering into the staple cartridge  3500 . In certain embodiments, the first inner layer  3512  can comprise a first medicament stored, or absorbed, therein and the second inner layer  3513  can comprise a second medicament stored, or absorbed, therein, wherein the second medicament can be different than the first medicament. In at least one embodiment, an initial compression of the cartridge body  3510 , which causes the rupture of the outer layer  3511 , can generally express the first medicament out of the first inner layer  3512  and a subsequent compression of the cartridge body  3510  can generally express the second medicament out of the second inner layer  3513 . In such embodiments, however, portions of the first medicament and the second medicament may be expressed simultaneously although a majority of the medicament that is initially expressed can be comprised of the first medicament and a majority of the medicament subsequently expressed thereafter can be comprised of the second medicament. In certain embodiments, further to the above, the first inner layer  3512  can be comprised of a more compressible material than the second inner layer  3513  such that the initial compression forces or pressure, which can be lower than the subsequent compression forces or pressure, can cause a larger initial deflection within the first inner layer  3512  than the second inner layer  3513 . This larger initial deflection within the first inner layer  3512  can cause a larger portion of the first medicament to be expressed from the first inner layer  3512  than the second medicament from the second inner layer  3513 . In at least one embodiment, the first inner layer  3512  can be more porous and/or more flexible than the second inner layer  3513 . In at least one such embodiment, the first inner layer  3512  can comprise a plurality of pores, or voids,  3508  defined therein and the second inner layer  3513  can comprise a plurality of pores, or voids,  3509  defined therein wherein, in various embodiments, the pores  3508  can be configured to store the first medicament in the first inner layer  3512  and the pores  3509  can be configured to store the second medicament in the second inner layer  3513 . In certain embodiments, the size and density of the pores  3508  within the first inner layer  3512  and the pores  3509  within the second inner layer  3513  can be selected so as to provide a desired result described herein. 
     In various embodiments, referring again to  FIGS. 60 and 61 , the outer layer  3511 , the first inner layer  3512 , and/or the second inner layer  3513  can be comprised of a bioabsorbable material. In at least one embodiment, the first inner layer  3512  can be comprised of a first bioabsorbable material, the second inner layer  3513  can be comprised of a second bioabsorbable material, and the outer layer  3511  can be comprised of a third bioabsorbable material, wherein the first bioabsorbable material, the second bioabsorbable material, and/or the third bioabsorbable material can be comprised of different materials. In certain embodiments, the first bioabsorbable material can be bioabsorbed at a first rate, the second bioabsorbable material can be bioabsorbed at a second rate, and the third bioabsorbable material can be bioabsorbed at a third rate, wherein the first rate, the second rate, and/or the third rate can be different. In at least one such embodiment, when a material is bioabsorbed at a particular rate, such a rate can be defined as the amount of material mass that is absorbed by a patient&#39;s body over a unit of time. As it is known, the bodies of different patients may absorb different materials at different rates and, thus, such rates may be expressed as average rates in order to account for such variability. In any event, a faster rate may be a rate in which more mass is bioabsorbed for a unit of time than a slower rate. In various embodiments, referring again to  FIGS. 60 and 61 , the first inner layer  3512  and/or the second inner layer  3513  can be comprised of a material which bioabsorbs faster than the material comprising the outer layer  3511 . In at least one such embodiment, the first inner layer  3512  and/or the second inner layer  3513  can be comprised of a bioabsorbable foam, tissue sealant, and/or haemostatic material, such as oxidized regenerated cellulose (ORC), for example, and the outer layer  3511  can be comprised of a buttress material and/or plastic material, such as polyglycolic acid (PGA) which is marketed under the trade name Vicryl, polylactic acid (PLA or PLLA), polydioxanone (PDS), polyhydroxyalkanoate (PHA), poliglecaprone 25 (PGCL) which is marketed under the trade name Monocryl, polycaprolactone (PCL), and/or a composite of PGA, PLA, PDS, PHA, PGCL and/or PCL, for example. In such embodiments, the first inner layer  3512  and/or the second inner layer  3513  can immediately treat the tissue and can reduce bleeding from the tissue, for example, wherein the outer layer  3514  can provide longer-term structural support and can be bioabsorbed at a slower rate. 
     Owing to the slower rate of bioabsorbability of the outer layer  3511 , further to the above, the outer layer  3511  can buttress or structurally reinforce the tissue within the staple line as it heals. In certain embodiments, one of the first inner layer  3512  and the second inner layer  3513  can be comprised of a material which can be bioabsorbed faster than the other such that, in at least one embodiment, one of the layers can provide an initial release of a therapeutic material and the other layer can provide a sustained release of the same therapeutic material and/or a different therapeutic material. In at least one such embodiment, the rate in which a therapeutic material can be released from a layer  3512 ,  3513  can be a function of the bioabsorbability of the substrate layer in which the medicament is absorbed or dispersed. For example, in at least one embodiment, the substrate comprising the first inner layer  3512  can be bioabsorbed faster than the substrate comprising the second inner layer  3513  and, as a result, a medicament can be release from the first inner layer  3512  faster than the second inner layer  3513 , for example. In various embodiments, as described herein, one or more of the layers  3511 ,  3512 , and  3513  of the cartridge body  3510  can be adhered to one another by at least one adhesive, such as fibrin and/or protein hydrogel, for example. In certain embodiments, the adhesive can be water soluble and can be configured to release the connection between the layers as the staple cartridge  3500  is being implanted and/or some time thereafter. In at least one such embodiment, the adhesive can be configured to bioabsorb faster than the outer layer  3511 , the first inner layer  3512 , and/or the second inner layer  3513 . 
     In various embodiments, referring now to  FIGS. 62 and 63 , a staple cartridge, such as staple cartridge  3600 , for example, can comprise a cartridge body  3610  including a compressible first layer  3611 , a second layer  3612  attached to the first layer  3611 , and a removable compressible layer  3613  attached to the second layer  3612 . In at least one such embodiment, the first layer  3611  can be comprised of a compressible foam material, the second layer  3612  can comprise a laminate material adhered to the first layer  3611  utilizing one or more adhesives, and the third layer  3613  can comprise a compressible foam material removably adhered to the second layer  3612  utilizing one or more adhesives, for example. In various embodiments, the staple cartridge  3600  can further comprise a plurality of staples, such as staples  3620 , for example, positioned in the cartridge body  3610 . In at least one such embodiment, each staple  3620  can comprise a base  3622  positioned in the third layer  3613  and one or more deformable legs  3621  extending upwardly from the base  3622  through the second layer  3612  and into the first layer  3611 , for example. In use, further to the above, the top surface  3619  of the staple cartridge body  3610  can be pushed downwardly by an anvil until the staple legs  3621  penetrate through the top surface  3619  and the targeted tissue and contact the anvil. After the staple legs  3621  have been sufficiently deformed, the anvil can be moved away from the staple cartridge  3600  such that the compressible layers thereof can at least partially re-expand. In various circumstances, the insertion of the staples through the tissue can cause the tissue to bleed. In at least one embodiment, the third layer  3613  can be comprised of an absorbent material, such as protein hydrogel, for example, which can draw blood away from the stapled tissue. In addition to or in lieu of the above, the third layer  3613  can be comprised of a haemostatic material and/or tissue sealant, such as freeze-dried thrombin and/or fibrin, for example, which can be configured to reduce the bleeding from the tissue. In certain embodiments, the third layer  3613  may provide a structural support to the first layer  3611  and the second layer  3612  wherein the third layer  3613  may be comprised of a bioabsorbable material and/or a non-bioabsorbable material. In any event, in various embodiments, the third layer  3613  can be detached from the second layer  3612  after the staple cartridge  3610  has been implanted. In embodiments where the third layer  3613  comprises an implantable-quality material, the surgeon can elect whether to remove the third layer  3613  of the cartridge body  3610 . In at least one embodiment, the third layer  3613  can be configured to be removed from the second layer  3612  in one piece. 
     In various embodiments, the first layer  3611  can be comprised of a first foam material and the third layer  3613  can be comprised of a second foam material which can be different than the first foam material. In at least one embodiment, the first foam material can have a first density and the second foam material can have a second density wherein the first density can be different than the second density. In at least one such embodiment, the second density can be higher than the first density wherein, as a result, the third layer  3613  may be less compressible, or have a lower compression rate, than the first layer  3611 . In at least one alternative embodiment, the first density can be higher than the second density wherein, as a result, the first layer  3611  may be less compressible, or have a lower compression rate, than the third layer  3613 . In various embodiments, referring now to  FIGS. 64 and 65 , a staple cartridge  3700 , similar to the staple cartridge  3600 , can comprise a cartridge body  3710  comprising a first compressible foam layer  3711 , a second layer  3712  attached to the first layer  3711 , and a detachable third compressible foam layer  3713  removably attached to the second layer  3712 . In at least one such embodiment, the third layer  3713  can comprise a plurality of staple receiving slots, or cut-outs,  3709  which can each be configured to receive at least a portion of a staple  3620 , such as a staple base  3622 , for example, therein. In certain embodiments, the staples  3620  can be configured to slide within the staple receiving slots  3709  or, stated another way, the third layer  3713  can be configured to slide relative to the staples  3620  when the staple cartridge  3700  is positioned against the targeted tissue and compressed by an anvil, for example. In at least one embodiment, the receiving slots  3709  can be configured such that there is clearance between the staples  3620  and the side walls of the receiving slots  3709 . In at least one such embodiment, as a result of the above, the staples  3620  may not capture a portion of the third layer  3713  therein when the staples  3620  are deformed, as illustrated in  FIGS. 64 and 65 . In certain other embodiments, the ends of the staple receiving slots  3709  adjacent to the second layer  3712  can be closed by a portion of the third layer  3713  and, as a result, at least a portion of the third layer  3713  can be captured within the staples  3620  when they are deformed. In any event, the third layer  3713  can comprise one or more perforations and/or score marks  3708 , for example, which can be configured to permit the third layer  3713  to be removed from the second layer  3712  in two or more pieces as illustrated in  FIG. 64 . In  FIG. 64 , one of the pieces of the third layer  3713  is illustrated as being removed by a tool  3755 . In various embodiments, the perforations  3708  can be arranged along a line positioned intermediate a first row of staples and a second row of staples. 
     In various embodiments, referring again to  FIGS. 64 and 65 , the bases  3622  of the staples  3620  can be positioned within the receiving slots  3709  wherein, in at least one embodiment, the side walls of the receiving slots  3709  can be configured to contact and releasable retain the staple legs  3621  in position. In certain embodiments, although not illustrated, the third layer  3713  can comprise an elongated slot surrounding all of the staples within a staple line. In at least one such embodiment, a staple cartridge comprising four staple rows, for example, can comprise an elongate slot aligned with each staple row in the bottom layer of the staple cartridge. Further to the above, at least a portion of the staple cartridge  3600  and/or the staple cartridge  3700  can be implanted within a patient and at least a portion of the staple cartridge can be removable from the patient. In at least one embodiment, referring again to  FIGS. 64 and 65 , the first layer  3711  and the second layer  3712  can be captured within the staples  3620  and can be implanted with the staples  3620 , whereas the third layer  3713  can be optionally removed or detached from the staple cartridge  3700 . In various circumstances, the removal of a portion of the implanted staple cartridge can reduce the amount of material that the patient&#39;s body has to reabsorb which can provide various therapeutic benefits. In the event that a portion of a staple cartridge is detached and removed, such as by a laparoscopic tool  3755 , for example, the detached staple cartridge portion can be removed from the surgical site through a trocar, such as a trocar having a 5 mm aperture, for example. In certain embodiments, a cartridge body can comprise more than one layer that can be removed. For example, the cartridge body  3710  can comprise a fourth layer wherein the third layer of  3713  of the cartridge body  3710  can be comprised of a haemostatic material and the fourth layer can be comprised of a support layer. In at least one such embodiment, a surgeon can remove the support layer and then elect whether to remove the haemostatic layer, for example. 
     In various embodiments, referring now to  FIG. 66 , a staple cartridge, such as staple cartridge  3800 , for example, can comprise a cartridge body  3810  including an outer layer  3811  and an inner layer  3812 . The inner layer  3812  can be comprised of a compressible foam material and the outer layer  3811  can be at leas partially wrapped around the inner layer  3812 . In at least one embodiment, the outer layer  3811  can comprise a first portion  3811   a  configured to be positioned on a first side of the inner layer  3812  and a second portion  3811   b  configured to be positioned on a second side of the inner layer  3812  wherein the first portion  3811   a  and the second portion  3811   b  can be connected by a flexible hinge, such as hinge  3809 , for example. In at least one such embodiment, at least one adhesive, such as fibrin and/or protein hydrogel, for example, can be applied to the first side and/or the second side of the inner layer  3812  in order to secure the portions of the outer layer  3811  thereto. In various embodiments, the outer layer  3811  can comprise one or more fastening members extending therefrom. In at least one such embodiment, the outer layer  3811  can comprise a plurality of deformable legs  3821  extending from one side of the outer layer  3811  which can be seated in the compressible inner layer  3812 . In at least one such embodiment, the legs  3821  may not protrude from the second side of the inner layer  3812  while, in at least one alternative embodiment, the legs  3821  may at least partially protrude from the inner layer  3812 . When the compressible cartridge body  3810  is compressed, in use, the legs  3821  can be configured to pierce the inner layer  3812  and the second portion  3811   b  of the outer layer  3811 . In certain embodiments, the second portion  3811   b  of the outer layer  3811  can comprise apertures, such as apertures  3808 , for example defined therein which can be configured to receive the staple legs  3821 . In certain embodiments, at least portions of the staple cartridge  3800  can comprise a knife slot  3803  which can be configured to slidably receive a cutting member therein. In at least one such embodiment, the knife slot  3803  may not extend entirely through the thickness of the cartridge body  3810  and, as a result, the cutting member may incise the cartridge body  3810  as it is moved relative thereto. 
     In various embodiments, referring now to  FIG. 67 , a staple cartridge  3900  can comprise, similar to staple cartridge  3800 , a cartridge body  3910  including an inner layer  3812  and an outer layer  3811 , wherein the outer layer  3811  can comprise a first portion  3811   a  positioned adjacent to the first side of the inner layer  3812  and a second portion  3811   b  positioned adjacent to the second side of the inner layer  3812 . In at least one embodiment, similar to the above, the outer layer  3811  can comprise one or more fastening members extending therefrom. In at least one such embodiment, the outer layer  3811  can comprise a plurality of deformable legs  3921  extending from one side of the outer layer  3811  which can be seated in the compressible inner layer  3812 . In certain embodiments, each deformable leg  3921  can comprise at least one hook or barb  3923  protruding therefrom which can be configured to engage the second portion  3811   b  of the outer layer  3811  and, as a result, retain the outer layer  3811  to the inner layer  3812 . In at least one such embodiment, the barbs  3923  can be configured to protrude from the second side of the inner layer  3812  and extend through the apertures  3808  in the second portion  3811   b  of the outer layer  3811  such that the barbs  3923  can engage the outside surface of the outer layer  3811  and lock the outer layer  3811  to the inner layer  3812 . In order to construct the staple cartridge  3900 , the inner layer  3812  may be at least partially compressed in order to cause the barbs to protrude therefrom and enter into the apertures  3808 . In at least one such embodiment, the staple cartridge  3900  can be at least partially pre-compressed when it is inserted into a staple cartridge, for example. In certain embodiments, further to the above, at least a portion of the legs  3921  can be embedded within the first portion  3811   a  of the outer layer  3811  wherein, in at least one embodiment, the outer layer  3811  can be comprised of a plastic material, such as polydioxanone (PDS) and/or polyglycolic acid (PGA), for example, and the plastic material can be overmolded around at least a portion of the legs  3921 . 
     In various embodiments, referring now to  FIGS. 68-72 , a staple cartridge, such as staple cartridge  4000 , for example, can comprise a cartridge body  4010  including a compressible first layer  4011  and a second layer  4012  and, in addition, a plurality of staples  4020  positioned within the cartridge body  4010 . In certain embodiments, referring to  FIG. 70 , each staple  4020  can comprise a base  4022  and at least one deformable leg  4023  extending from the base  4022 . In at least one embodiment, referring to  FIG. 68 , the staple cartridge  4000  can be positioned between a staple cartridge channel  4030  and an anvil  4040  of an end effector of a surgical stapler wherein the second layer  4012  of the cartridge body  4010  and/or the bases  4022  of the staples  4020  can be positioned against the staple cartridge channel  4030 . In various embodiments, referring now to  FIG. 69 , the second layer  4012  can comprise a layer of pledgets  4060  interconnected to one another by a pledget support frame  4061 . In at least one such embodiment, the pledgets  4060  and the pledget support frame  4061  can be comprised of a molded plastic material, such as polyglycolic acid (PGA), for example. Each pledget  4060  can comprise one or more apertures or slots  4062  which can be configured to receive a staple leg  4021  extending therethrough as illustrated in  FIGS. 70 and 71 . Each pledget  4060  can further comprise a receiving slot  4063  defined therein which can be configured to receive a base  4022  of a staple  4020 . In various embodiments, referring again to  FIG. 69 , the pledgets  4060  and/or pledget support fame  4061  can comprise a plurality of score marks, perforations, or the like which can be configured to allow the pledgets  4060  to become detached from the pledget support frame  4061  at a desired location. Similarly, referring to  FIG. 71 , one or more pledgets  4060  can be connected to one another along a line comprising perforations and/or score marks  4064 , for example. In use, the compressible foam layer  4011  can be positioned against the targeted tissue T and the cartridge body  4010  can be compressed by the anvil  4040  such that the anvil  4040  can deform the staples  4020 . When the staples  4020  are deformed, the staple legs  4021  of each staple  4020  can capture the tissue T, a portion of the first layer  4011 , and a pledget  4060  within the deformed staple. When the staple cartridge channel  4030  is moved away from the implanted staple cartridge  4060 , for example, the pledget support frame  4061  can be detached from the pledgets  4060  and/or the pledgets  4060  can be detached from one another. In certain circumstances, the pledgets  4060  can be detached from the frame  4061  and/or each other when the staples  4020  are being deformed by the anvil  4040  as described above. 
     In various embodiments described herein, the staples of a staple cartridge can be fully formed by an anvil when the anvil is moved into a closed position. In various other embodiments, referring now to  FIGS. 73-76 , the staples of a staple cartridge, such as staple cartridge  4100 , for example, can be deformed by an anvil when the anvil is moved into a closed position and, in addition, by a staple driver system which moves the staples toward the closed anvil. The staple cartridge  4100  can comprise a compressible cartridge body  4110  which can be comprised of a foam material, for example, and a plurality of staples  4120  at least partially positioned within the compressible cartridge body  4110 . In various embodiments, the staple driver system can comprise a driver holder  4160 , a plurality of staple drivers  4162  positioned within the driver holder  4160 , and a staple cartridge pan  4180  which can be configured to retain the staple drivers  4162  in the driver holder  4160 . In at least one such embodiment, the staple drivers  4162  can be positioned within one or more slots  4163  in the driver holder  4160  wherein the sidewalls of the slots  4163  can assist in guiding the staple drivers  4162  upwardly toward the anvil. In various embodiments, the staples  4120  can be supported within the slots  4163  by the staple drivers  4162  wherein, in at least one embodiment, the staples  4120  can be entirely positioned in the slots  4163  when the staples  4120  and the staple drivers  4162  are in their unfired positions. In certain other embodiments, at least a portion of the staples  4120  can extend upwardly through the open ends  4161  of slots  4163  when the staples  4120  and staple drivers  4162  are in their unfired positions. In at least one such embodiment, referring primarily now to  FIG. 74 , the bases of the staples  4120  can be positioned within the driver holder  4160  and the tips of the staples  4120  can be embedded within the compressible cartridge body  4110 . In certain embodiments, approximately one-third of the height of the staples  4120  can be positioned within the driver holder  4160  and approximately two-thirds of the height of the staples  4120  can be positioned within the cartridge body  4110 . In at least one embodiment, referring to  FIG. 73A , the staple cartridge  4100  can further comprise a water impermeable wrap or membrane  4111  surrounding the cartridge body  4110  and the driver holder  4160 , for example. 
     In use, the staple cartridge  4100  can be positioned within a staple cartridge channel, for example, and the anvil can be moved toward the staple cartridge  4100  into a closed position. In various embodiments, the anvil can contact and compress the compressible cartridge body  4110  when the anvil is moved into its closed position. In certain embodiments, the anvil may not contact the staples  4120  when the anvil is in its closed position. In certain other embodiments, the anvil may contact the legs of the staples  4120  and at least partially deform the staples  4120  when the anvil is moved into its closed position. In either event, the staple cartridge  4100  can further comprise one or more sleds  4170  which can be advanced longitudinally within the staple cartridge  4100  such that the sleds  4170  can sequentially engage the staple drivers  4162  and move the staple drivers  4162  and the staples  4120  toward the anvil. In various embodiments, the sleds  4170  can slide between the staple cartridge pan  4180  and the staple drivers  4162 . In embodiments where the closure of the anvil has started the forming process of the staples  4120 , the upward movement of the staples  4120  toward the anvil can complete the forming process and deform the staples  4120  to their fully formed, or at least desired, height. In embodiments where the closure of the anvil has not deformed the staples  4120 , the upward movement of the staples  4120  toward the anvil can initiate and complete the forming process and deform the staples  4120  to their fully formed, or at least desired, height. In various embodiments, the sleds  4170  can be advanced from a proximal end of the staple cartridge  4100  to a distal end of the staple cartridge  4100  such that the staples  4120  positioned in the proximal end of the staple cartridge  4100  are fully formed before the staples  4120  positioned in the distal end of the staple cartridge  4100  are fully formed. In at least one embodiment, referring to  FIG. 75 , the sleds  4170  can each comprise at least one angled or inclined surface  4711  which can be configured to slide underneath the staple drivers  4162  and lift the staple drivers  4162  as illustrated in  FIG. 76 . 
     In various embodiments, further to the above, the staples  4120  can be formed in order to capture at least a portion of the tissue T and at least a portion of the compressible cartridge body  4110  of the staple cartridge  4100  therein. After the staples  4120  have been formed, the anvil and the staple cartridge channel  4130  of the surgical stapler can be moved away from the implanted staple cartridge  4100 . In various circumstances, the cartridge pan  4180  can be fixedly engaged with the staple cartridge channel  4130  wherein, as a result, the cartridge pan  4180  can become detached from the compressible cartridge body  4110  as the staple cartridge channel  4130  is pulled away from the implanted cartridge body  4110 . In various embodiments, referring again to  FIG. 73 , the cartridge pan  4180  can comprise opposing side walls  4181  between which the cartridge body  4110  can be removably positioned. In at least one such embodiment, the compressible cartridge body  4110  can be compressed between the side walls  4181  such that the cartridge body  4110  can be removably retained therebetween during use and releasably disengaged from the cartridge pan  4180  as the cartridge pan  4180  is pulled away. In at least one such embodiment, the driver holder  4160  can be connected to the cartridge pan  4180  such that the driver holder  4160 , the drivers  4162 , and/or the sleds  4170  can remain in the cartridge pan  4180  when the cartridge pan  4180  is removed from the surgical site. In certain other embodiments, the drivers  4162  can be ejected from the driver holder  4160  and left within the surgical site. In at least one such embodiment, the drivers  4162  can be comprised of a bioabsorbable material, such as polyglycolic acid (PGA) which is marketed under the trade name Vicryl, polylactic acid (PLA or PLLA), polydioxanone (PDS), polyhydroxyalkanoate (PHA), poliglecaprone 25 (PGCL) which is marketed under the trade name Monocryl, polycaprolactone (PCL), and/or a composite of PGA, PLA, PDS, PHA, PGCL and/or PCL, for example. In various embodiments, the drivers  4162  can be attached to the staples  4120  such that the drivers  4162  are deployed with the staples  4120 . In at least one such embodiment, each driver  4162  can comprise a trough configured to receive the bases of the staples  4120 , for example, wherein, in at least one embodiment, the troughs can be configured to receive the staple bases in a press-fit and/or snap-fit manner. 
     In certain embodiments, further to the above, the driver holder  4160  and/or the sleds  4170  can be ejected from the cartridge pan  4180 . In at least one such embodiment, the sleds  4170  can slide between the cartridge pan  4180  and the driver holder  4160  such that, as the sleds  4170  are advanced in order to drive the staple drivers  4162  and staples  4120  upwardly, the sleds  4170  can move the driver holder  4160  upwardly out of the cartridge pan  4180  as well. In at least one such embodiment, the driver holder  4160  and/or the sleds  4170  can be comprised of a bioabsorbable material, such as polyglycolic acid (PGA) which is marketed under the trade name Vicryl, polylactic acid (PLA or PLLA), polydioxanone (PDS), polyhydroxyalkanoate (PHA), poliglecaprone 25 (PGCL) which is marketed under the trade name Monocryl, polycaprolactone (PCL), and/or a composite of PGA, PLA, PDS, PHA, PGCL and/or PCL, for example. In various embodiments, the sleds  4170  can be integrally formed and/or attached to a drive bar, or cutting member, which pushes the sleds  4170  through the staple cartridge  4100 . In such embodiments, the sleds  4170  may not be ejected from the cartridge pan  4180  and may remain with the surgical stapler while, in other embodiments in which the sleds  4170  are not attached to the drive bar, the sleds  4170  may be left in the surgical site. In any event, further to the above, the compressibility of the cartridge body  4110  can allow thicker staple cartridges to be used within an end effector of a surgical stapler as the cartridge body  4110  can compress, or shrink, when the anvil of the stapler is closed. In certain embodiments, as a result of the staples being at least partially deformed upon the closure of the anvil, taller staples, such as staples having an approximately 0.18″ staple height, for example, could be used, wherein approximately 0.12″ of the staple height can be positioned within the compressible layer  4110  and wherein the compressible layer  4110  can have an uncompressed height of approximately 0.14″, for example. 
     In various embodiments, referring now to  FIGS. 77-80 , a staple cartridge, such as staple cartridge  4200 , for example, can comprise a compressible cartridge body  4210 , a plurality of staples  4220  positioned therein, and a plurality of flexible lateral support members  4234 . In various embodiments, referring now to  FIG. 78 , the staple cartridge  4200  can be positioned intermediate an anvil  4240  and a staple cartridge channel  4230  wherein, in at least one embodiment, the lateral support members  4234  can be attached to the staple cartridge channel  4230 . When the anvil  4240  is moved downwardly to compress the cartridge body  4210  and at least partially deform the staples  4220 , as illustrated in  FIG. 79 , the side portions of the cartridge body  4210  can bulge laterally and push the lateral support members  4234  outwardly. In at least one such embodiment, the lateral support members  4234  can be attached to the cartridge body  4210  and, when the cartridge body  4210  bulges laterally as described above, the lateral support members  4234  can detach from the cartridge body  4210  as illustrated in  FIG. 79 . In at least one embodiment, the lateral support members  4234  can be adhered to the cartridge body  4210  utilizing at least one adhesive, such as fibrin and/or protein hydrogel, for example. Similar to the above, the closing of the anvil  4240  may only partially deform the staples  4220 , wherein the formation of the staples  4220  can be completed by the advancement of one or more sleds  4270  through the staple cartridge  4200  as illustrated in  FIG. 80 . In various embodiments, referring now to  FIGS. 82 and 83 , the sleds  4270  can be advanced from a proximal end of the staple cartridge  4200  to a distal end of the staple cartridge  4200  by a cutting member  4280 . In at least one such embodiment, the cutting member  4280  can comprise a cutting element, or knife,  4283 , which can be advanced through the tissue T and/or the compressible cartridge body  4210 . In certain embodiments, the cutting member  4280  can comprise camming members  4282  which can travel along the outside surfaces of the jaws  4230  and  4240  and move or hold the jaws in position. In various embodiments, as a result of the above, the staples  4220  can be formed into their final shapes at the same time, or at least substantially the same time, as the tissue T is incised. In at least one such embodiment, the sleds  4270  can be positioned distally with respect to the knife  4283  such that the tissue T is only incised when the proceeding portion of the tissue has been fully stapled, for example. 
     In various embodiments, referring again to  FIGS. 82 and 83 , the sleds  4270  can comprise separate slidable members which are advanced together by the cutting member  4280 . In at least one such embodiment, the sleds  4270  can be contained within the staple cartridge  4200  and the cutting member  4280  can be advanced into the staple cartridge  4200  by a firing bar  4281  such that the cutting member  4280  engages the sleds  4270  and advances the sleds  4270  distally. In certain embodiments, the sleds  4270  can be connected to one another. In either event, each sled  4270  can comprise an angled surface, or cam,  4271  which can be configured to lift the staples  4220  aligned within a staple row. In certain embodiments, the angled surfaces  4271  can be integrally formed with the cutting member  4280 . In at least one embodiment, referring again to  FIGS. 82 and 83 , each staple  4200  can comprise a base, at least one deformable member extending from the base, and a crown  4229  overmolded onto and/or positioned around at least a portion of the base and/or the deformable members of the staple  4200 . In various embodiments, such crowns  4229  can be configured to be driven directly by a sled  4270 , for example. More particularly, in at least one embodiment, the crowns  4229  of staples  4220  can be configured such that the angled surfaces  4271  of the sleds  4270  can slide underneath and directly contact the crowns  4229  without a staple driver positioned therebetween. In such embodiments, each crown  4229  can comprise at least one co-operating angled or inclined surface which can be engaged by an angled surface  4271  of the sleds  4270  such that the co-operating angled surfaces can drive the staples  4220  upwardly when the sleds  4270  are slid underneath the staples  4220 . 
     In various embodiments, referring now to  FIG. 81 , a staple cartridge, such as staple cartridge  4300 , for example, can comprise a compressible body  4310  and a plurality of staples  4320  positioned within the compressible body  4310 . Similar to the above, the staple cartridge  4300  can comprise flexible lateral supports  4334  which can be attached to a staple cartridge channel and/or adhered to the compressible body  4310 . In addition to the above, the flexible lateral supports  4334  can be connected together by one or more struts, or connection members,  4335  which can be configured to hold the lateral supports  4334  together. In use, the connection members  4335  can be configured to prevent, or at least inhibit, the lateral supports  4334  from becoming prematurely detached from the cartridge body  4310 . In certain embodiments, the connection members  4335  can be configured to hold the lateral supports  4334  together after the staple cartridge  4300  has been compressed by an anvil. In such embodiments, the lateral supports  4334  can resist the lateral bulging, or displacement, of the lateral portions of the cartridge body  4310 . In certain embodiments, a cutting member, such as cutting member  4280 , for example, can be configured to transect the connection members  4335  as the cutting member  4280  is moved distally within the cartridge body  4310 . In at least one such embodiment, the cutting member  4280  can be configured to push one or more sleds, such as sleds  4270 , for example, distally in order to form the staples  4320  against an anvil. The sleds  4270  can lead the cutting edge  4283  such that the cutting member  4280  does not transect a connection member  4335  until the staples  4320  adjacent to that connection member  4335  have been fully formed, or at least formed to a desired height. In various circumstances, the connection members  4335 , in co-operation with the lateral supports  4334 , can prevent, or at least reduce, the lateral movement of the compressible cartridge body  4310  and, concurrently, prevent, or at least reduce, the lateral movement of the staples  4320  positioned within the cartridge body  4310 . In such circumstances, the connection members  4335  can hold the staples  4320  in position until after they are deformed and the connection members  4335  can be thereafter cut to release the lateral portions of the cartridge body  4310 . As mentioned above, the lateral supports  4334  can be connected to the staple cartridge channel and, as a result, can be removed from the surgical site with the staple cartridge channel after the staple cartridge  4300  has been implanted. In certain embodiments, the lateral supports  4334  can be comprised of an implantable material and can be left within a surgical site. In at least one embodiment, the connection members  4335  can be positioned intermediate the cartridge body  4310  and the tissue T and, after the connection members  4335  have been detached from the lateral supports  4334 , the connections members  4335  can remain implanted in the patient. In at least one such embodiment, the connection members  4335  can be comprised of an implantable material and, in certain embodiments, the connection members  4335  can be comprised of the same material as the lateral supports  4334 , for example. In various embodiments, the connection members  4335  and/or lateral supports  4334  can be comprised of a flexible bioabsorbable material such as polyglycolic acid (PGA) which is marketed under the trade name Vicryl, polylactic acid (PLA or PLLA), polydioxanone (PDS), polyhydroxyalkanoate (PHA), poliglecaprone 25 (PGCL) which is marketed under the trade name Monocryl, polycaprolactone (PCL), and/or a composite of PGA, PLA, PDS, PHA, PGCL and/or PCL, for example. In various embodiments, a connection member can comprise a sheet of material connecting the lateral supports  4334 . In certain embodiments, a staple cartridge can comprise connection members extending across the top surface of the cartridge body  4310  and, in addition, connection members extending around the bottom surface of the cartridge body  4310 . 
     In various embodiments, referring now to  FIG. 84 , a staple cartridge can comprise staples, such as staples  4420 , for example, which can comprise a wire portion inserted into a crown portion. In at least one embodiment, the wire portion can be comprised of metal, such as titanium and/or stainless steel, for example, and/or plastic, such as polydioxanone (PDS) and/or polyglycolic acid (PGA), for example. In at least one embodiment, the crown portion can be comprised of metal, such as titanium and/or stainless steel, for example, and/or plastic, such as polydioxanone (PDS) and/or polyglycolic acid (PGA), for example. In certain embodiments, the wire portion of each staple  4420  can comprise a base  4422  and deformable legs  4421  extending from the base  4422  wherein the crown portion of each staple  4420  can comprise a crown  4429  which can be configured to receive at least a portion of a base  4422  therein. In order to assemble the portions of each staple  4420 , referring now to  FIGS. 85A-85C , the legs  4421  of the wire portion can be inserted into an opening  4426  in a crown  4429  wherein the opening  4426  can be configured to guide the legs  4421  into a base chamber  4427 . The wire portion can be further inserted into the crown  4429  such that the legs  4421  exit the base chamber  4427  and the base  4422  of the wire portion enters into the base chamber  4427 . In at least one such embodiment, the base chamber  4427  can be configured such that the wire portion is rotated within the crown  4429  as the base  4422  enters into the base chamber  4427  such that the staple legs  4421  are pointed in an upward, or at least substantially upward, direction. In various embodiments, referring again to  FIG. 84 , the crown  4429  can comprise exit holes  4425  which can be configured to receive the staple legs  4421  therein. 
     In various embodiments, further to the above, a surgical stapler can comprise a sled  4470  configured to transverse the staple cartridge  4400  and staple cartridge channel  4430  and move the staples  4420  contained within the cartridge body  4410  toward an anvil. In various circumstances, the sled  4470  can be moved from a proximal end of the staple cartridge channel  4430  to a distal end of the cartridge channel  4430  in order to implant the cartridge body  4410  and the staples  4420 . In certain circumstances, the sled  4470  can be retracted or returned to the proximal end of the cartridge channel  4430  and another staple cartridge  4400  can be inserted into the cartridge channel  4430 . Once the new staple cartridge  4400  has been positioned within the cartridge channel  4430 , the sled  4470  can be advanced distally once again. In various embodiments, the surgical stapler may comprise one or more lock-out features which can prevent the sled  4470  from being advanced distally once again without a new staple cartridge  4400  being positioned within the cartridge channel  4430 . In at least one such embodiment, referring again to  FIG. 84 , the staple cartridge channel  4430  can comprise a lock-out shoulder  4439  which can be configured to prevent, or at least limit, the distal movement of the sled  4470 . More particularly, the sled  4470  can be configured to abut the shoulder  4439  unless the sled  4470  is at least partially lifted upwardly over the shoulder  4439  by a lift feature  4428 , for example, extending between the proximal-most staples  4420  within a staple cartridge  4400 . Stated another way, absent the presence of the proximal-most staples  4420  in a new staple cartridge  4400 , the sled  4470  cannot be advanced. Thus, when an expended staple cartridge  4400  is present within the cartridge channel  4430 , or no staple cartridge  4400  is present in the cartridge channel  4430  at all, the sled  4470  cannot be advanced within the cartridge channel  4430 . 
     Further to the above, referring now to  FIG. 86 , a staple cartridge, such as staple cartridge  4500 , for example, can be positioned within a staple cartridge channel  4530  and can comprise a compressible cartridge body  4510 , a plurality of staples  4520  positioned within the cartridge body  4510 , and a cartridge pan, or retainer,  4580 . In various embodiments, the compressible cartridge body  4510  can comprise an outer layer  4511  and an inner layer  4512  wherein, in at least one embodiment, the outer layer  4511  can sealingly enclose the inner layer  4512 . In at least one such embodiment, the outer layer  4511  can extend between the inner layer  4512  and the cartridge pan  4580 . In certain other embodiments, the outer layer  4511  may only partially surround the inner layer  4512  and, in at least one such embodiment, the outer layer  4511  and the cartridge pan  4580  can co-operate to encompass, or at least substantially encompass, the inner layer  4512 . In various embodiments, further to the above, the staples  4520  can be supported by the cartridge pan  4580  wherein the cartridge pan  4580  can comprise one or more staple support channels configured to support the staples  4520 . In certain embodiments, the cartridge pan  4580  can be attached to the cartridge body  4510  wherein, in at least one such embodiment, the cartridge body  4510  can be compressed laterally between opposing side walls of the cartridge pan  4580 . In various embodiments, the side walls of the cartridge pan  4580  can support the cartridge body  4510  laterally and, in at least one such embodiment, the cartridge pan  4580  can comprise one or more walls, or fins,  4582  extending upwardly from the bottom support  4583  into the cartridge body  4510 . In at least one such embodiment, the cartridge body  4510  can comprise one or more slots, or channels, therein which can be configured to receive and/or interlock with the walls  4582 . In various embodiments, the walls  4582  can extend partially, or almost entirely, through the cartridge body  4510 . In at least one such embodiment, the walls  4582  can extend longitudinally through the staple cartridge  4500  between a first row of staples  4520  and a second row of staples  4520 . 
     In various embodiments, the cartridge body  4510  and/or the cartridge pan  4580  can comprise co-operating retention features which can provide a snap-fit between the cartridge pan  4580  and the cartridge body  4510 . In certain embodiments, the staple cartridge  4500  can be positioned within the cartridge channel  4530  such that the cartridge pan  4580  is positioned against and/or attached to the cartridge channel  4530 . In at least one embodiment, the cartridge pan  4580  can be detachably coupled to the cartridge channel  4530  such that, after the staple cartridge  4500  has been compressed by the anvil  4540  and the staples  4520  have been deformed, the cartridge pan  4580  can detach from the cartridge channel  4530  and can be implanted with the cartridge body  4510 . In at least one such embodiment, the cartridge pan  4580  can be comprised of a bioabsorbable material such as polyglycolic acid (PGA) which is marketed under the trade name Vicryl, polylactic acid (PLA or PLLA), polydioxanone (PDS), polyhydroxyalkanoate (PHA), poliglecaprone 25 (PGCL) which is marketed under the trade name Monocryl, polycaprolactone (PCL), and/or a composite of PGA, PLA, PDS, PHA, PGCL and/or PCL, for example. In certain embodiments, a surgical stapler can further comprise a firing mechanism and/or driver which can be slid intermediate the staple cartridge channel  4530  and a bottom drive surface on the cartridge pan  4580  which can be configured to lift or eject the cartridge pan  4580  from the cartridge channel  4530 . In certain embodiments, the cartridge body  4510  can be detachably coupled to the cartridge pan  4580  such that, after the staple cartridge  4500  has been compressed by the anvil  4540  and the staples  4520  have been deformed, the cartridge body  4510  can detach from the cartridge pan  4580 . In at least one such embodiment, the cartridge pan  4580  can remain fixedly engaged with the cartridge channel  4530  such that the cartridge pan  4580  is removed from the surgical site with the cartridge channel  4530 . In certain embodiments, a surgical stapler can further comprise a firing mechanism and/or driver which can be slid intermediate the staple cartridge pan  4580  and a bottom drive surface on the cartridge body  4510  which can be configured to lift or eject the cartridge body  4510  from the cartridge pan  4580 . In at least one such embodiment, the staple cartridge  4500  can further comprise staple drivers positioned intermediate the cartridge pan  4580  and the staples  4520  such that, as the firing mechanism is slid distally, the staple drivers and the staples  4520  can be driven upwardly toward the anvil. In at least one such embodiment, the staple drivers can be at least partially embedded within the compressible cartridge body  4510 . 
     In various embodiments, similar to the above, the staple cartridge  4500  can comprise a lock-out feature which can be configured to prevent, or at least limit, the distal movement of a cutting member unless a unfired staple cartridge  4500  has been positioned within the staple cartridge channel  4530 . In certain embodiments, the staple cartridge pan  4580  can comprise a surface which lifts the cutting member upwardly and over a locking surface within the staple cartridge channel  4530 , for example. In the event that a staple cartridge  4500  comprising a cartridge pan  4580  is not present in the cartridge channel  4530 , the cutting member cannot be advanced. In at least one embodiment, the proximal-most staples, and/or any other suitable staples, within a staple cartridge  4500  can comprise a lifting surface which can sufficiently lift the cutting member over the locking surface. In addition to or in lieu of the above, various portions of the staple cartridge  4500  can be comprised of materials having different colors. In such embodiments, a surgeon may be able to visually identify when an unfired and/or fired staple cartridge is present in the staple cartridge channel  4530 . In at least one such embodiment, the outer layer  4511  of the cartridge body  4510  may have a first color, the cartridge pan  4580  may have a second color, and the staple cartridge channel  4530  may have a third color. In the event that the surgeon sees the first color, the surgeon may know that an unfired cartridge  4500  is present in the staple cartridge channel  4530 ; in the event that the surgeon sees the second color, the surgeon may know that a fired cartridge  4500  is present in the staple cartridge channel  4530  and that the remaining cartridge pan  4580  needs to be removed; and in the event that the surgeon sees the third color, the surgeon may know that no portion of a staple cartridge  4500  remains within the cartridge channel  4530 . 
     In various embodiments, referring now to  FIG. 87 , a staple cartridge, such as staple cartridge  4600 , for example, can comprise a compressible, implantable cartridge body  4610  and a plurality of staples  4620  positioned therein. The cartridge body  4610  can comprise an outer layer  4611  and an inner layer  4612 . In certain embodiments, the inner layer  4612  can comprise a plurality of pockets, such as pockets, or cavities,  4615 , for example, defined therein which can facilitate the collapse of the cartridge body  4610 . In at least one such embodiment, the inner layer  4612  can comprise a corrugated, or honeycomb-configured, lattice which can be configured to withstand a compressive force, or pressure, as long as the compressive force, or pressure, does not exceed a certain threshold value. When the threshold value has not been exceeded, the inner layer  4612  can deform at a linear, or at least substantially linear, rate with respect to the compressive force, or pressure, being applied. After the compressive force, or pressure, has exceeded the threshold value, the inner layer  4612  can suddenly succumb to large deflections and collapse, or buckle, as a result of the compressive load. In various embodiments, the lattice of the inner layer  4612  can be comprised of a plurality of sub-layers  4612   a  which can be connected together. In at least one embodiment, each sub-layer  4612   a  can comprise a plurality of alternating furrows and ridges, or waves, which can be aligned with the alternating furrows and ridges of an adjacent sub-layer  4612   a . In at least one such embodiment, the furrows of a first sub-layer  4612   a  can be positioned adjacent to the ridges of a second sub-layer  4612   a  and, similarly, the ridges of the first sub-layer  4612   a  can be positioned adjacent to the furrows of the second sub-layer  4612   a . In various embodiments, the adjacent sub-layers  4612   a  can be adhered to one another and/or the outer layer  4611  by at least one adhesive, such as fibrin and/or protein hydrogel, for example.  FIG. 88  illustrates the staple cartridge  4600  after the cartridge body  4610  has been collapsed and the staples  4620  have been deformed in order to capture and hold tissue T against the cartridge body  4610 . 
     In various embodiments, referring now to  FIGS. 89-91 , a staple cartridge, such as staple cartridge  4700 , for example, can comprise a compressible, implantable cartridge body  4710  and a plurality of staples  4720  positioned within the cartridge body  4710 . Similar to the above, the cartridge body  4710  can comprise an outer layer  4711  and an inner layer  4712 , wherein the inner layer  4712  can comprise a plurality of sub-layers  4712   a . Also similar to the above, each sub-layer  4712   a  can comprise alternating furrows  4717  and ridges  4718  which can be aligned with one another to define pockets, or cavities,  4715  therebetween. In at least one such embodiment, the furrows  4717  and/or the ridges  4718  can extend along axes which are parallel to one another and/or parallel to a longitudinal axis  4709 . In various embodiments, the staples  4720  can be aligned in a plurality of staple rows which can extend along axes which are parallel to one another and/or parallel to the longitudinal axis  4709 . In various alternative embodiments, referring again to  FIGS. 87 and 88 , the staples  4620  contained in the cartridge body  4600  can extend along axes which are traverse or perpendicular with respect to the axes defined by the furrows and ridges of the sub-layers  4612   a . Referring again to  FIGS. 89-91 , the staples  4720  can extend through the furrows  4717  and the ridges  4718  wherein friction forces between the staples  4720  and the sub-layers  4712   a  can hold the staples  4720  within the cartridge body  4710 . In certain embodiments, the plurality of sub-layers  4712   a  can be comprised of a buttress material and/or plastic material, such as polydioxanone (PDS) and/or polyglycolic acid (PGA), for example, which can be configured to hold the staples  4720  in an upright orientation, for example, and/or hold the staples  4720  in alignment with respect to each other as illustrated in  FIGS. 89 and 90 .  FIG. 91  illustrates the staple cartridge  4700  after the cartridge body  4710  has been collapsed and the staples  4720  have been deformed in order to capture and hold tissue T against the cartridge body  4710 . 
     In various embodiments, referring again to  FIGS. 89-91 , the cartridge body  4710  can resiliently or elastically collapse when it is compressed. In at least one such embodiment, the waves formed within each sub-layer  4712   a  by the furrows  4717  and the ridges  4718  can be flattened, or at least substantially flattened, when the cartridge body  4710  is compressed which can collapse, or at least substantially collapse, the cavities  4715  defined therebetween. In various circumstances, the cartridge body  4710 , or at least portions of the cartridge body  4710 , can resiliently or elastically re-expand after the compressive force, or pressure, has been removed from the cartridge body  4710 . In at least one such embodiment, the connections between the furrows  4717  and the ridges  4718  of adjacent sub-layers  4712   a  can remain intact, or at least substantially intact, when the cartridge body  4710  is compressed such that, after the compression force has been removed from the cartridge body  4710 , the sub-layers  4712   a  can bias themselves away from each other and, as a result, at least partially re-expand the cartridge body  4710 . In certain embodiments, the cartridge body  4710  can be plastically deformed, or crushed, when it is compressed and, as a result, the cartridge body  4710  may not re-expand after the compressive force, or pressure, has been removed from the cartridge body  4710 . In certain embodiments, referring now to  FIG. 92 , a staple cartridge, such as staple cartridge  4800 , for example, can comprise a crushable cartridge body  4810  comprising an outer layer  4811  and an inner layer  4812 , wherein the inner layer  4812  can comprise a corrugated, honeycomb-configured, lattice having a plurality of pockets, or cavities,  4815  defined therein. In various embodiments, the walls defining the lattice of inner layer  4812  can comprise one or more weakened, or thin, cross-sections  4819  which can be configured to allow the walls defining the lattice to break when the cartridge body  4810  is compressed. In such circumstances, the cartridge body  4810  can be crushed when the staple cartridge  4800  is implanted. 
     In various embodiments, referring now to  FIGS. 93-95 , a staple cartridge, such as staple cartridge  4900 , for example, can comprise a cartridge body  4910  comprising an outer layer  4911  and a plurality of collapsible elements  4912  positioned intermediate top and bottom portions of the outer layer  4911 , for example. Referring primarily to  FIGS. 93 and 94 , the staple cartridge  4900  can further comprise a plurality of staples  4920 , wherein each staple  4920  can be positioned in a collapsible element  4912 . More particularly, each collapsible element  4912  can comprise a first portion  4912   a , a second portion  4012   b , and a third portion  4012   c  which can co-operate to define a cavity  4915  therein which is configured to receive a staple  4920 . In use, further to the above, the staple cartridge  4900  can be positioned within a staple cartridge channel and a compressive force can be applied to the tissue contacting surface  4919  in order to compress the cartridge body  4910 . As the tissue contacting surface  4919  is moved downwardly, the collapsible elements  4912  can collapse. In such circumstances, the second portion  4912   b  of each collapsible element  4912  can collapse into a corresponding first portion  4912   a  and, similarly, the third portion  4912   c  of each collapsible element  4912  can collapse into a corresponding second portion  4912   b . As the cartridge body  4910  is compressed and the collapsible elements  4912  are collapsed, the staples  4920  positioned within the collapsible elements  4912  can be deformed, as illustrated in  FIG. 95 . In various embodiments, the second portion  4912   b  of each collapsible element  4912  can be frictionally engaged and/or press-fit within a corresponding first portion  4912   a  such that, once the compressive force applied to the collapsible element  4912  exceeds the retention force retaining the first portion  4912   a  and the second portion  4912   b  in their extended position ( FIG. 94 ), the first portion  4912   a  and the second portion  4912   b  can begin to slide relative to one another. Similarly, the third portion  4912   c  of each collapsible element  4912  can be frictionally engaged and/or press-fit within a corresponding second portion  4912   b  such that, once the compressive force applied to the collapsible element  4912  exceeds the retention force retaining the second portion  4912   b  and the third portion  4912   c  in their extended position ( FIG. 94 ), the second portion  4912   b  and the third portion  4912   c  can begin to slide relative to one another. 
     In many embodiments described herein, a staple cartridge can comprise a plurality of staples therein. In various embodiments, such staples can be comprised of a metal wire deformed into a substantially U-shaped configuration having two staple legs. Other embodiments are envisioned in which staples can comprise different configurations such as two or more wires that have been joined together having three or more staple legs. In various embodiments, the wire, or wires, used to form the staples can comprise a round, or at least substantially round, cross-section. In at least one embodiment, the staple wires can comprise any other suitable cross-section, such as square and/or rectangular cross-sections, for example. In certain embodiments, the staples can be comprised of plastic wires. In at least one embodiment, the staples can be comprised of plastic-coated metal wires. In various embodiments, a cartridge can comprise any suitable type of fastener in addition to or in lieu of staples. In at least one such embodiment, such a fastener can comprise pivotable arms which are folded when engaged by an anvil. In certain embodiments, two-part fasteners could be utilized. In at least one such embodiment, a staple cartridge can comprise a plurality of first fastener portions and an anvil can comprise a plurality of second fastener portions which are connected to the first fastener portions when the anvil is compressed against the staple cartridge. In certain embodiments, as described above, a sled or driver can be advanced within a staple cartridge in order to complete the forming process of the staples. In certain embodiments, a sled or driver can be advanced within an anvil in order to move one or more forming members downwardly into engagement with the opposing staple cartridge and the staples, or fasteners, positioned therein. 
     In various embodiments described herein, a staple cartridge can comprise four rows of staples stored therein. In at least one embodiment, the four staple rows can be arranged in two inner staple rows and two outer staple rows. In at least one such embodiment, an inner staple row and an outer staple row can be positioned on a first side of a cutting member, or knife, slot within the staple cartridge and, similarly, an inner staple row and an outer staple row can be positioned on a second side of the cutting member, or knife, slot. In certain embodiments, a staple cartridge may not comprise a cutting member slot; however, such a staple cartridge may comprise a designated portion configured to be incised by a cutting member in lieu of a staple cartridge slot. In various embodiments, the inner staple rows can be arranged within the staple cartridge such that they are equally, or at least substantially equally, spaced from the cutting member slot. Similarly, the outer staple rows can be arranged within the staple cartridge such that they are equally, or at least substantially equally, spaced from the cutting member slot. In various embodiments, a staple cartridge can comprise more than or less than four rows of staples stored within a staple cartridge. In at least one embodiment, a staple cartridge can comprise six rows of staples. In at least one such embodiment, the staple cartridge can comprise three rows of staples on a first side of a cutting member slot and three rows of staples on a second side of the cutting member slot. In certain embodiments, a staple cartridge may comprise an odd number of staple rows. For example, a staple cartridge may comprise two rows of staples on a first side of a cutting member slot and three rows of staples on a second side of the cutting member slot. In various embodiments, the staple rows can comprise staples having the same, or at least substantially the same, unformed staple height. In certain other embodiments, one or more of the staple rows can comprise staples having a different unformed staple height than the other staples. In at least one such embodiment, the staples on a first side of a cutting member slot may have a first unformed height and the staples on a second side of a cutting member slot may have a second unformed height which is different than the first height, for example. 
     In various embodiments, referring now to  FIGS. 96A-96D , an end effector of a surgical stapler can comprise a cartridge attachment portion, such as staple cartridge channel  5030 , for example, a fastener cartridge removably positioned in the staple cartridge channel  5030 , such as staple cartridge  5000 , for example, and a jaw  5040  positioned opposite the staple cartridge  5000  and the staple cartridge channel  5030 . The staple cartridge  5000  can comprise a compressible body  5010  and a plurality of staples  5020 , and/or any other suitable fasteners, at least partially positioned in the compressible body  5010 . In at least one such embodiment, each staple  5020  can comprise a base  5022  and, in addition, legs  5021  extending upwardly from the base  5022 , wherein at least a portion of the legs  5021  can be embedded in the cartridge body  5010 . In various embodiments, the compressible body  5010  can comprise a top, or tissue-contacting, surface  5019  and a bottom surface  5018 , wherein the bottom surface  5018  can be positioned against and supported by a support surface  5031  of the staple cartridge channel  5030 . Similar to the above, the support surface  5031  can comprise a plurality of support slots  5032  ( FIG. 96D ), for example, defined therein which can be configured to receive and support the bases  5022  of the staples  5020 . In various embodiments, the end effector of the surgical stapler can further comprise a retention matrix, such as retention matrix  5050 , for example, which can be configured to engage the staples  5020  and capture tissue therebetween. In at least one such embodiment, the retention matrix  5050  can be removably mounted to the jaw  5040 . In use, once the staple cartridge  5000  has been positioned within the staple cartridge channel  5030 , the jaw  5040 , and the retention matrix  5050  attached thereto, can be moved toward the staple cartridge  5000  and the staple cartridge channel  5030 . In at least one embodiment, the jaw  5040  can be moved downwardly along an axis  5099  such that the jaw  5040  and the staple cartridge channel  5030  remain parallel, or at least substantially parallel, to one another as the jaw  5040  is closed. More particularly, in at least one such embodiment, the jaw  5040  can be closed in a manner such that a tissue-contacting surface  5051  of the retention matrix  5050  is parallel, or at least substantially parallel, to the tissue-contacting surface  5019  of the staple cartridge  5000  as the jaw  5040  is moved toward the staple cartridge  5000 . 
     In various embodiments, referring now to  FIG. 96A , the retention matrix  5050  can be detachably secured to the jaw  5040  such that there is little, if any, relative movement between the retention matrix  5050  and the jaw  5040  when the retention matrix  5050  is attached to the jaw  5040 . In at least one embodiment, the jaw  5040  can comprise one or more retention features which can be configured to hold the retention matrix  5050  in position. In at least one such embodiment, the retention matrix  5050  can be snap-fit and/or press-fit into the jaw  5040 . In certain embodiments, the retention matrix  5050  can be adhered to the jaw  5040  utilizing at least one adhesive. In any event, the jaw  5040  can be moved into a position in which the retention matrix  5050  is in contact with the tissue T and the tissue T is positioned against the tissue-contacting surface  5019  of the staple cartridge  5000 . When the tissue T is positioned against the staple cartridge  5000  by the jaw  5040 , the compressible body  5010  of the staple cartridge  5000  may or may not be compressed by the jaw  5040 . In either circumstance, in various embodiments, the legs  5021  of the staples  5200  may not protrude through the tissue-contacting surface  5019  of the staple cartridge  5000  as illustrated in  FIG. 96A . Furthermore, as also illustrated in  FIG. 96A , the jaw  5040  can hold the tissue T against the compressible body  5010  without engaging the retention matrix  5050  with the staples  5020 . Such embodiments can permit a surgeon to open and close the jaw  5040  multiple times in order to obtain a desired positioning of the end effector within a surgical site, for example, without damaging the tissue T. Other embodiments are envisioned, however, where the staple tips  5023  can protrude from the tissue-contacting surface  5019  prior to the cartridge body  5010  being compressed by the anvil  5040 . Once the end effector has been suitably positioned, referring now to  FIG. 96B , the jaw  5040  can be moved downwardly toward the staple cartridge channel  5030  such that the compressible body  5010  is compressed by the anvil  5040  and such that the tissue-contacting surface  5019  is pushed downwardly relative to the staples  5020 . As the tissue-contacting surface  5019  is pushed downwardly, the tips  5023  of the staple legs  5021  can pierce the tissue-contacting surface  5019  and pierce at least a portion of the tissue T. In such circumstances, the retention matrix  5050  may be positioned above the staples  5020  such that the retention apertures  5052  of retention matrix  5050  are aligned, or at least substantially aligned, with the tips  5023  of the staple legs  5021 . 
     As the retention matrix  5050  is pushed downwardly along the axis  5099 , referring now to  FIG. 96C , the staple legs  5021  of staples  5020  can enter into the retention apertures  5052 . In various embodiments, the staple legs  5021  can engage the side walls of the retention apertures  5052 . In certain embodiments, as described in greater detail below, the retention matrix  5050  can comprise one or more retention members extending into and/or around the retention apertures  5052  which can engage the staple legs  5021 . In either event, the staple legs  5021  can be retained in the retention apertures  5052 . In various circumstances, the tips  5023  of the staple legs  5021  can enter into the retention apertures  5052  and can frictionally engage the retention members and/or the side walls of the apertures  5052 . As the retention matrix  5050  is pushed toward the bases  5022  of the staples  5020 , the staple legs  5021  can slide relative to the side walls and/or the retention members. As a result of the above, sliding friction forces can be created between the staple legs  5021  and the retention matrix  5050  wherein such sliding friction forces can resist the insertion of the retention matrix  5050  onto the staples  5020 . In various embodiments, the sliding friction forces between the retention matrix  5050  and the staples  5020  can be constant, or at least substantially constant, as the retention matrix  5050  is slid downwardly along the staple legs  5021  of the staples  5020 . In certain embodiments, the sliding friction forces may increase and/or decrease as the retention matrix  5050  is slid downwardly along the staple legs  5021  owing to variations in geometry of the staple legs  5021 , the retention apertures  5052 , and/or the retention members extending into and/or around the retention apertures  5052 , for example. In various embodiments, the insertion of the retention matrix  5050  onto the staples  5020  can also be resisted by the compressible body  5010  of the staple cartridge  5000 . More particularly, the compressible body  5010  can be comprised of an elastic material, for example, which can apply a resistive force to the retention matrix  5050  which increases as the distance in which the compressible body  5010  is compressed increases. In at least one such embodiment, the increase in the resistive force generated by the cartridge body  5010  can be linearly proportional, or at least substantially linearly proportional, with respect to the distance in which the cartridge body  5010  is compressed. In certain embodiments, the increase in the resistive force generated by the cartridge body  5010  can be geometrically proportional with respect to the distance in which the cartridge body  5010  is compressed. 
     In various embodiments, further to the above, a sufficient firing force can be applied to the jaw  5040  and the retention matrix  5050  in order to overcome the resistive and friction forces described above. In use, the retention matrix  5050  can be seated to any suitable depth with respect to the staples  5020 . In at least one embodiment, the retention matrix  5050  can be seated to a depth with respect to the bases  5022  of the staples  5020  in order to secure two or more layers of tissue together and generate compressive forces, or pressure, within the tissue. In various circumstances, the system comprising the retention matrix  5050  and the staples  5020  can allow a surgeon to select the amount of compressive forces, or pressure, that is applied the tissue by selecting the depth in which the retention matrix  5050  is seated. For example, the retention matrix  5050  can be pushed downwardly toward the staple bases  5022  of the staples  5020  until the retention matrix  5050  is seated a certain depth  5011  away from the bottom of the support slots  5032 , wherein a shorter depth  5011  can result in higher compressive forces, or pressure, being applied to the tissue T than a taller depth  5011  which can result in lower compressive forces, or pressure, being applied to the tissue T. In various embodiments, the compressive forces, or pressures, applied to the tissue T can be linearly proportional, or at least substantially linearly proportional, to the depth  5011  in which the retention matrix  5050  is seated. In various circumstances, the compressive forces, or pressure, applied to the tissue T can depend on the thickness of the tissue T positioned between the retention matrix  5050  and the staple cartridge  5020 . More particularly, for a given distance  5011 , the presence of thicker tissue T can result in higher compression forces, or pressure, than the presence of thinner tissue T. 
     In various circumstances, further to the above, a surgeon can adjust the depth in which the retention matrix  5050  is seated in order to account for thicker and/or thinner tissue positioned within the end effector and to apply a certain or predetermined pressure to the tissue T regardless of the tissue thickness. For example, the surgeon can seat the retention matrix  5050  to a shorter depth  5011  when fastening thinner tissue T or a taller depth  5011  when fastening thicker tissue T in order to arrive at the same, or at least substantially the same, compression pressure within the tissue. In certain embodiments, further to the above, a surgeon can selectively determine the amount of compressive pressure to apply to the tissue T positioned between the retention matrix  5050  and the staple cartridge  5010 . In various circumstances, a surgeon can engage the retention matrix  5050  with the staples  5020  and position the retention matrix  5050  a first distance away from the bases  5022  of the staples  5020  in order to apply a first compressive pressure to the tissue. The surgeon can alternatively position the retention matrix  5050  a second distance away from the bases  5022 , which is shorter than the first distance, in order to apply a second compressive pressure to the tissue which is greater than the first pressure. The surgeon can alternatively position the retention matrix  5050  a third distance away from the bases  5022 , which is shorter than the second distance, in order to apply a third compressive pressure to the tissue which is greater than the second pressure. In various embodiments, the fastening system comprising the retention matrix  5050  and the staples  5020  can be configured to permit a surgeon to apply a wide range of compressive pressures to the targeted tissue. 
     In various embodiments, referring now to  FIG. 96D , the staple legs  5021  can be inserted through the retention matrix  5050  such that the staple leg tips  5023  extend above the top surface of the retention matrix  5050 . In at least one embodiment, referring again to  FIG. 96C , the jaw  5040  can further comprise clearance apertures  5042  defined therein which can be configured to receive the staple leg tips  5023  as they pass through the retention apertures  5052  in the retention matrix  5050 . In at least one such embodiment, the clearance apertures  5042  can be aligned with the retention apertures  5052  such that the legs  5021  do not contact the jaw  5040 . In various embodiments, the clearance apertures  5042  can have a sufficient depth such that the staple legs  5021  do not contact the jaw  5040  regardless of the distance in which the retention matrix  5050  is seated. After the retention matrix  5050  has been engaged with the staples  5020  and seated to a desired position, referring now to  FIG. 96D , the staple cartridge channel  5030  and the jaw  5040  can be moved away from the tissue T. More particularly, the staple cartridge channel  5030  can be detached from the implanted staple cartridge  5000  and the anvil  5040  can be detached from the implanted retention matrix  5050 . As the jaw  5040  is moved away from the retention matrix  5050  and the staple supports  5032  are moved away from the staple bases  5022 , the distance  5011  between the retention matrix  5050  and the bottom of the bases  5022  can be maintained eventhough the jaw  5040  and the staple cartridge channel  5030  are no longer providing support thereto. In various embodiments, the static friction forces between the staple legs  5021  and the retention matrix  5050  can be sufficient to maintain the retention matrix  5050  in position despite a biasing force being applied to the retention matrix  5050  by the compressed cartridge body  5010  and/or the compressed tissue T. In at least one such embodiment, the cartridge body  5010  can be comprised of a resilient material which, when compressed, can apply an elastic biasing force to the retention matrix  5050  and the staples  5020  in a manner which tends to push the retention matrix  5050  and the staples  5020  apart, although such movement is opposed by the frictional engagement between the staple legs  5021  and the retention matrix  5050 . 
     In various embodiments, as described above, a retention matrix can comprise a plurality of retention apertures, wherein each retention aperture can be configured to receive a leg of a fastener therein. In at least one embodiment, referring now to  FIG. 97 , a portion of a retention matrix  5150  is illustrated therein which can comprise a retention aperture  5152  defined by a perimeter  5156 . In various embodiments, the perimeter  5156  of the aperture  5152  can comprise a circular, or at least substantially circular, profile and/or any other suitable profile. In certain embodiments, the retention matrix  5150  can comprise one or more retention members, such as retention members  5153 , for example, which extend into the aperture  5152  and can be configured to engage a fastener leg when the fastener leg is inserted therethrough. In at least one such embodiment, each retention member  5153  can comprise a cantilever which extends inwardly toward a center axis  5159 , i.e., toward the center of the aperture  5152 . In various embodiments, each cantilever can comprise a first end which is attached to the retention matrix body  5158  and a second end which forms the perimeter  5156  of the retention aperture  5152 . In certain embodiments, the perimeter  5156  of a retention aperture  5152  can be defined by a first diameter, or width, and a fastener leg can be defined by a second diameter, or width, wherein the second diameter can be larger than the first diameter. In at least one such embodiment, the fastener leg can be configured to contact and deflect one or more of the retention members  5153  in order to increase the diameter of the retention aperture  5152  as the fastener leg is being inserted therethrough. In certain embodiments, further to the above, the fastener leg can define a perimeter which is larger than the perimeter  5156  of the retention aperture  5152  such that the fastener leg can expand the perimeter  5156  when the fastener leg is inserted therein. 
     In various embodiments, referring again to  FIG. 97 , the aperture  5152  can be defined by the deformable members  5153 , wherein each deformable member  5153  can be configured to deflect relative to, or independently of, the other deformable members  5153 . In at least one such embodiment, adjacent deformable members  5153  can be separated by slots  5154  which can be configured to permit each deformable member  5153  to flex relative to the others. In certain embodiments, each slot  5154  can comprise a first end  5155  in the retention matrix body  5158 , a second end opening into the retention aperture  5152 , and a constant, or at least substantially constant, width extending between the first end  5155  and the second end. In various other embodiments, the width of each slot  5154  may not be constant and each slot  5154  may increase and/or decrease in width between the first and second ends thereof. In certain embodiments, the first ends  5155  of the slots  5154  can comprise an enlarged portion, such as a circular portion, which can provide, one, strain relief to the bases of the deformable members  5153  attached to the retention matrix body  5158  and, two, means for increasing the flexibility of the deformable members  5153 . In various embodiments, the geometry of the deformable members  5153 , and/or slots  5154 , can be selected so as to provide the deformable members  5153  with a desired flexibility. In certain embodiments, for example, the slots  5154  can be lengthened in order to create longer deformable members  5153  which can be more flexible than deformable members  5153  having a shorter length. In at least one embodiment, the width of each deformable member  5153  can be selected so as to provide a desired flexibility thereof. More particularly, deformable members having a thinner width can be more flexible than deformable members having a thicker width. In certain embodiments, referring again to  FIG. 97 , the first ends of the cantilevers of deformable members  5153  attached to the retention matrix body  5158  can be wider than the second ends of the cantilevers. In at least one such embodiment, the cantilevers can be tapered in a linear, or at least substantially linear, manner between the first and second ends thereof. 
     In various embodiments, referring again to  FIG. 97 , the retention matrix body  5158  can comprise a flat, or at least substantially flat, sheet of material having a tissue-contacting surface  5151  and a top surface  5157 . In at least one such embodiment, the tissue-contacting surface  5151  and the top surface  5157  can be parallel, or at least substantially parallel, to one another. In various embodiments, each deformable member  5153  can comprise a first portion  5153   a  and a second portion  5153   b , wherein the first portion  5153   a  can extend in a first direction and the second portion  5153   b  can extend in a different, or second, direction. In at least one such embodiment, the retention matrix body  5158  can define a plane and the first portions  5153   a  of the deformable members  5153  can lie within such a plane. In various embodiments, the second portions  5153   b  of the deformable members  5153  can extend at an angle relative to the first portions  5153   a . In at least one such embodiment, the second portions  5153   b  can extend in directions which are pointed away from the top surface  5157  of the retention matrix body  5158  and, in certain embodiments, the second portions  5153   b  can converge toward the central axis  5159  of the retention aperture  5152 . In any event, in various embodiments, the second portions  5153   b  can be configured to deflect away from the central axis  5159  when the fastener leg is inserted therethrough. In embodiments where a staple leg  5021  of a staple  5020  is inserted into a retention aperture  5152 , the deformable members  5153  can deform in a direction which is generally away from the bases  5122  of the staples  5120 . In certain embodiments, as a result, the deformable members  5153  can deflect in a general direction which is the same as, or at least substantially the same as, the direction in which the staple legs  5021  are being inserted. 
     In various embodiments, referring again to  FIG. 97 , the second portions  5153   b  of the deformable members  5153  can each comprise a sharp tip, for example, which can be configured to slide against a staple leg  5021  as the staple leg  5021  is inserted therein. The sharp tips of the second portions  5153   b  can also be configured to bite into the staple leg  5021  in the event that the staple leg  5021  were to be pulled in the opposite direction, i.e., in a direction which would remove the staple leg  5021  from the retention aperture  5052 . In certain circumstances, the second portions  5153   b  can be inclined at an angle relative to the side of the staple leg  5021  which is greater than 90 degrees and, as a result, the second portions  5153   b  may dig, or burrow, into the side of the staple leg  5021  when the staple leg  5021  experiences a force which tends to withdraw the staple leg  5021  from the retention aperture  5052 . In certain embodiments, the staple legs  5021  can comprise indentations and/or concavities, such as microindentations, for example, in the surfaces thereof which can be configured to receive the tips of the deformable members  5053 , for example, therein. In at least one such embodiment, the tips of the deformable members  5053  can catch in and burrow into the indentations in the staple legs  5021  when a withdrawing force is applied to the staple legs  5021 . In various embodiments, as a result of the burrowing of the second portions  5153   b  into the staple legs  5021 , forces acting to remove the staple legs  5021  from the retention apertures  5022  may only seat the second portions  5153   b  deeper into the staple legs  5021  and increase the force required to remove the staple legs  5021 . Furthermore, owing to the upward inclination of the second portions  5153   b , in at least one embodiment, the second portions  5153   b  can be more permissive to the insertion of a staple leg  5021  within a retention aperture  5152  and more resistive to withdrawal of the staple leg  5021 . In at least one embodiment, as a result, the force required to insert a staple leg  5021  into a retention aperture  5022  may be less than the force required to remove the staple leg  5021  from the retention aperture  5022 . In various embodiments, the force needed to remove the staple leg  5021  from the retention aperture  5022  can be approximately 50 percent greater than the force needed to insert the staple leg  5021  into the retention aperture  5022 , for example. In various other embodiments, the force needed to remove the staple leg  5021  may between approximately 10 percent and approximately 100 percent greater than the force needed to insert the staple leg  5021 , for example. In certain embodiments, the force needed to remove the staple leg  5021  may be approximately 100 percent, approximately 150 percent, approximately 200 percent, and/or greater than approximately 200 percent larger than the force needed to insert the staple leg  5021 , for example. 
     In certain embodiments, referring again to  FIG. 97 , the second portions  5153   b  can be arranged circumferentially around the aperture  5152  and can define a pocket therebetween. More particularly, the second portions  5153   b  can define a pocket  5160  which can be configured to receive the tip of the fastener leg when it is inserted into the retention aperture  5152 . In various embodiments, the second portions  5153   b  of the deformable members  5153  can comprise an annular, or an at least substantially annular, contour which can co-operatively define an annular, or at least substantially annular, profile of the pocket  1560 , for example. In at least one such embodiment, the second portions  5153   b  can define a conical or frustoconical pocket. In various embodiments, the pocket can be defined by a suitable number of deformable members, such as four deformable members  5153  ( FIG. 97 ), six deformable members  5153  ( FIG. 98 ), or eight deformable members  5153  ( FIG. 99 ), for example. In certain embodiments, referring now to  FIG. 100 , the deformable members of a retention matrix, such as retention matrix  5250 , for example, can form a pyramidal shape, or an at least substantially pyramidal shape, for example. In various embodiments, a retention matrix  5250  can comprise a plurality of retention apertures, such as retention aperture  5252 , for example, which can be defined by a perimeter  5256 . In various embodiments, the perimeter  5256  can comprise a polygonal, or at least substantially polygonal, profile and/or any other suitable profile. In certain embodiments, the retention matrix  5250  can comprise one or more retention members, such as retention members  5253 , for example, which extend into the aperture  5252  and can be configured to engage a fastener leg when the fastener leg is inserted therethrough. In at least one such embodiment, each retention member  5253  can comprise a cantilever which extends inwardly toward a center axis  5259 , i.e., toward the center of the aperture  5252 . In various embodiments, each cantilever can comprise a first end which is attached to the retention matrix body  5258  and a second end which forms the perimeter  5256  of the retention aperture  5252 . In certain embodiments, the perimeter  5256  of a retention aperture  5252  can be defined by a first diameter, or width, and a fastener leg can be defined by a second diameter, or width, wherein the second diameter can be larger than the first diameter. In at least one such embodiment, the fastener leg can be configured to contact and deflect one or more of the retention members  5253  in order to increase the diameter of the retention aperture  5252  as the fastener leg is being inserted therethrough. In certain embodiments, further to the above, the fastener leg can define a perimeter which is larger than the perimeter  5256  of the retention aperture  5252  such that the fastener leg can expand the perimeter  5256  when the fastener leg is inserted therein. 
     In various embodiments, referring again to  FIG. 100 , the aperture  5252  can be defined by the deformable members  5253 , wherein each deformable member  5253  can be configured to deflect relative to, or independently of, the other deformable members  5253 . In at least one such embodiment, adjacent deformable members  5253  can be separated by slots  5254  which can be configured to permit each deformable member  5253  to flex relative to the others. In various embodiments, the retention matrix body  5258  can comprise a flat, or at least substantially flat, sheet of material having a tissue-contacting surface  5251  and a top surface  5257 . In at least one such embodiment, the tissue-contacting surface  5251  and the top surface  5257  can be parallel, or at least substantially parallel, to one another. In various embodiments, each deformable member  5253  can comprise a first portion  5253   a  and a second portion  5253   b , wherein the first portion  5253   a  can extend in a first direction and the second portion  5253   b  can extend in a different, or second, direction. In at least one such embodiment, the retention matrix body  5258  can define a plane and the first portions  5253   a  of the deformable members  5253  can lie within such a plane. In various embodiments, the second portions  5253   b  of the deformable members  5253  can extend at an angle relative to the first portions  5253   a . In at least one such embodiment, the second portions  5253   b  can extend in directions which are pointed away from the top surface  5257  of the retention matrix body  5258  and, in certain embodiments, the second portions  5253   b  can converge toward the central axis  5259  of the retention aperture  5252 . In any event, in various embodiments, the second portions  5253   b  can be configured to deflect away from the central axis  5259  when the fastener leg is inserted therethrough. In certain embodiments, referring again to  FIG. 100 , the second portions  5253   b  can be arranged circumferentially around the aperture  5252  and can define a pocket therebetween. More particularly, the second portions  5253   b  can define a pocket which can be configured to receive the tip of the fastener leg when it is inserted into the retention aperture  5252 . In various embodiments, the second portions  5253   b  of the deformable members  5253  can define a polygonal, or an at least substantially polygonal, pocket, for example. In various embodiments, the pocket can be defined by a suitable number of deformable members, such as four deformable members  5253  ( FIG. 100 ) which can define a square, six deformable members  5253  ( FIG. 101 ) which can define a hexagon, or eight deformable members  5253  ( FIG. 102 ) which can define an octagon, for example. 
     In various embodiments, referring now to  FIG. 103 , a retention matrix, such as retention matrix  5350 , for example, can be formed from a flat, or an at least substantially flat, sheet of material such as titanium and/or stainless steel, for example. In at least one such embodiment, a plurality of apertures  5352  can be formed in the body  5358  of the retention matrix  5350  by one or more stamping processes. The sheet of material can be positioned in a stamping die which, when actuated, can punch out certain portions of the material in order to form slots  5354 , apertures  5355  of slots  5354 , and/or the perimeter  5356  of the retention aperture  5352 , for example. The stamping die can also be configured to bend the deformable members  5353  in a suitable configuration. In at least one such embodiment, the stamping die can deform the second portions  5353   b  upwardly relative to the first portions  5353   a  along a crease line  5353   c . In various embodiments, referring now to  FIG. 104 , a retention matrix, such as retention matrix  5450 , for example, can comprise a plurality of retention apertures  5452 . Similar to the above, the perimeter  5456  of each retention aperture  5452  can be defined by a plurality of deformable members  5453  separated by slots, or slits,  5454 . In at least one such embodiment, the entirety of each deformable member  5453  can be bent upwardly wherein the free ends of the cantilevers comprising the deformable members  5453  can define the perimeter  5456 . In various embodiments, the retention matrix  5450  can comprise a plurality of apertures  5455  surrounding, or at least substantially surrounding, the retention aperture  5452 . In at least one such embodiment, the apertures  5455  can be arranged in a circular array surrounding or enclosing a perimeter defined by the fixed ends of the cantilevers of the deformable members  5453 . In certain embodiments, each aperture  5455  can comprise a circular, or at least substantially circular, perimeter and/or any other suitable perimeter. In use, the apertures  5455  can provide, one, strain relief to the bases of the deformable members  5453  attached to the retention matrix body  5458  and, two, means for increasing the flexibility of the deformable members  5453 . In various embodiments, larger apertures  5455  can provide more flexibility to the deformable members  5453  as compared to smaller apertures  5455 . Furthermore, apertures  5455  which are closer to the deformable members  5453  can provide more flexibility as compared to apertures  5455  which are further away. 
     In various embodiments, referring now to  FIG. 105 , a retention matrix, such as retention matrix  5550 , for example, can comprise a plurality of retention apertures  5552 . Each retention aperture  5552  can comprise an elongate slot  5554  having enlarged circular, or at least substantially circular, ends  5555 . In at least one such embodiment, the ends  5555  can be defined by a diameter which is wider than the slot  5554 . In certain embodiments, the elongate slot  5554  and the ends  5555  can positioned along, and/or centered along, a longitudinal axis  5559 . In various embodiments, the slot  5554  and the ends  5555  can define two opposing tabs  5553  which can be configured to engage a leg of a fastener and deflect as the fastener leg is inserted therethrough. In at least one embodiment, ends  5555  having a larger perimeter, or diameter, can define longer tabs  5553  which can be more flexible than tabs  5553  defined by ends  5555  having a smaller perimeter, or diameter. In various embodiments, the ends  5555  can have the same perimeter and diameter and, in at least one such embodiment, each tab  5553  can be symmetrical about an axis which is perpendicular, or at least substantially perpendicular, to the longitudinal axis  5559 . Alternatively, the ends  5555  can have different perimeters and/or diameters wherein, in at least one embodiment, each tab  5553  may not be symmetrical about its axis. In at least one such alternative embodiment, the tabs  5553  may twist about their axes as the fastener leg is inserted through the retention aperture  5552 . In various embodiments, referring now to  FIG. 106 , a retention matrix, such as retention matrix  5650 , for example, can comprise a plurality of retention apertures  5652 . Each retention aperture  5652  can comprise an elongate slot  5654  comprising circular, or at least substantially circular, ends  5655 . In at least one such embodiment, the elongate slot  5654  and the ends  5655  can be positioned along, and/or centered along, a longitudinal axis  5659 . In various embodiments, each end  5655  can be defined by a diameter which is the same as, or at least substantially the same as, the width of the slot  5654 . 
     In various embodiments, referring now to  FIG. 107 , a retention matrix, such as retention matrix  5750 , for example, can comprise a plurality of retention apertures  5752 . Each retention aperture  5752  can comprise a plurality of slots, such as slots  5754 , for example, having enlarged ends  5755 . In at least one such embodiment, the slots  5754  and the ends  5755  can be positioned along and/or centered along longitudinal axes  5759 . In various embodiments, the axes  5759  can extend in directions which are perpendicular or transverse to one another. In certain embodiments, the slots  5754  and the ends  5755  can define four tabs  5753 , for example, which can be configured to engage a fastener leg and deflect when the fastener leg is inserted through the retention aperture  5752 . In at least one embodiment, each tab  5753  can comprise a triangular, or at least substantially triangular, configuration, such as an equilateral triangle, for example. In various other embodiments, referring now to  FIG. 108 , a retention matrix, such as retention matrix  5850 , for example, can comprise a plurality of retention apertures  5852 . Each retention aperture  5852  can comprise a plurality of slots, such as slots  5854 , for example, having ends  5855 , wherein the slots  5854  and the ends  5855  can be positioned along and/or centered along longitudinal axes  5859 . In various embodiments, the axes  5859  can extend in directions which are perpendicular or transverse to one another. In certain embodiments, the slots  5854  and the ends  5855  can define tabs  5853  which can be configured to engage a fastener leg and deflect when the fastener leg is inserted through the retention aperture  5852 . In at least one embodiment, each tab  5853  can comprise an arcuate profile. More particularly, each tab  5853  can comprise a curved end, as opposed to a pointed end depicted in  FIG. 105 , which can be configured to contact the fastener leg. 
     In various embodiments, referring now to  FIG. 109 , a retention matrix, such as retention matrix  5950 , for example, can comprise a plurality of retention apertures  5952 . Each retention aperture  5952  can comprise a plurality of slots, such as slots  5954 , for example, wherein each slot  5954  can extend along, and/or can be centered along, an axis  5959 . In various embodiments, the axes  5959  can be transverse to each other and, in at least one such embodiment, the axes  5959  can be arranged such that all of the axes  5959  extend through a center of the retention aperture  5952  and are spaced equidistantly, or at least substantially equidistantly, from each other. In at least one embodiment, each slot  5954  can comprise an open end facing the center of the retention aperture  5952  and a second, or closed, end  5955  at the opposite end of the slot  5954 . Similar to the above, the slots  5954  and the ends  5955  can define three tabs  5953 , for example, which can be configured to engage a fastener leg and deflect when the fastener leg is inserted into the retention aperture  5952 . In various embodiments, each tab  5953  can comprise an arcuate configuration extending between adjacent ends  5955  of the slots  5954 . In various embodiments, referring now to  FIG. 110 , a retention matrix, such as retention matrix  6050 , for example, can comprise a plurality of retention apertures  6052 . Each retention aperture  6052  can comprise a tab  6053  which can be configured to engage a fastener leg and to deflect when the fastener leg is inserted into the retention aperture  6052 . In at least one such embodiment, the tab  6053  can comprise a base fixed to the retention matrix body  6058  and a free end comprising an arcuate or curved profile  6056  which can be configured to contact the fastener leg. In certain embodiments, the fastener leg can be a staple leg comprised of a round wire wherein the curved profile  6056  can be configured to match, or at least substantially match, a curved outer surface of the round wire. 
     In various embodiments, referring again to  FIG. 110 , the retention matrix body  6058  can comprise a plurality of slots  6054  and apertures  6055  which can be configured to define the tab  6053  and various portions of the retention aperture  6052 . In at least one embodiment, the tab  6053  can comprise a rectangular configuration comprising parallel, or at least substantially parallel, sides. In certain embodiments, referring now to  FIG. 111 , a retention matrix, such as retention matrix  6150 , for example, can comprise a plurality of retention apertures  6152 . Each retention aperture  6152  can comprise a tab  6153  which can be configured to engage a fastener leg and to deflect when the fastener leg is inserted into the retention aperture  6152 . In at least one such embodiment, the tab  6153  can comprise a base fixed to the retention matrix body  6158  and a free end comprising an arcuate or curved profile  6156  which can be configured to contact the fastener leg. In various embodiments, the retention matrix body  6158  can comprise a plurality of slots  6154  and apertures  6155  which can be configured to define the tab  6153  and various portions of the retention aperture  6152 . In at least one embodiment, the tab  6153  can comprise a tapered configuration comprising arcuate sides. In at least one such embodiment, the tab  6153  can taper geometrically with the base being wider than the free end, for example. 
     In various embodiments, as described above, a fastening system can comprise a plurality of staples comprising staple legs which are inserted through a plurality of retention apertures in a retention matrix. In certain embodiments, as described in greater detail below, the staples can be held in a first jaw and the retention matrix can be held in a second jaw, wherein at least one of the first jaw and the second jaw can be moved toward the other. In various circumstances, the staples positioned within the first jaw can be secured therein such that the staple legs are aligned with the retention apertures when the retention matrix is engaged with the staple legs. In certain embodiments, referring to  FIGS. 112 and 113 , a fastener system can comprise a staple cartridge  6200 , for example, positioned in a first jaw of a surgical stapler and a retention matrix  6250 , for example, positioned in a second jaw of the surgical stapler. Referring now to  FIGS. 119 and 120 , further to the above, the retention matrix  6250  can comprise a plurality of retention apertures  6252 , wherein each retention aperture  6252  can comprise a perimeter  6256  defined by one or more deflectable members  6253 . In at least one such embodiment, further to the above, the deflectable members  6253  defining each aperture  6252  can define a pocket  6201 . In various embodiments, each pocket  6201  can comprise a curved and/or concave surface, for example, which can be configured to guide a tip of a staple leg into the aperture  6252  in the event that the staple leg is misaligned with the retention aperture  6252  and initially contacts the deflectable members  6253  and/or the tissue-contacting surface  6251 , for example. 
     In various embodiments, further to the above, the fastening system can further comprise a plurality of staples  6220  comprising staple legs  6221  which can be inserted through the retention apertures  6252  in the retention matrix  6250 . In at least one such embodiment, each staple  6220  can comprise a substantially U-shaped configuration, for example, comprising a base  6222  from which the staple legs  6221  can extend upwardly. In various embodiments, referring now to  FIGS. 115 and 116 , the retention apertures  6252  in the retention matrix  6250  can be arranged in two parallel, or at least substantially parallel, longitudinal rows, for example, which can extend along, or parallel to, a longitudinal axis of the retention matrix. In certain embodiments, the retention apertures  6252  in a first row can be offset, or staggered, with respect to the retention apertures  6252  in a second row. In at least one such embodiment, each staple  6220  can comprise a first staple leg  6221  positioned in a retention aperture  6252  in the first row of and a second staple leg  6221  positioned in a retention aperture  6252  in the second row wherein, as a result, the bases  6222  can extend in a direction which is transverse to the longitudinal axis of the retention matrix  6250 . In at least one such embodiment, the staples  6220  can be parallel, or at least substantially parallel, to one another. More particularly, a base  6222   a  of a staple  6220   a  be parallel to, or at least substantially parallel to, a base  6222   b  of a staple  6220   b  which can be parallel to, or at least substantially parallel to, a base  6222   c  of a staple  6220   c , for example. In at least one embodiment, the staple legs  6221   a  of staple  6220   a  can define a plane which is parallel to, or at least substantially parallel to, a plane defined by the staple legs  6221   b  of staple  6220   b  which can be parallel to, or at least substantially parallel to, a plane defined by the staple legs  6221  of staple  6220   c , for example. 
     In various embodiments, referring now to  FIGS. 112 and 114 , the staple cartridge  6200  can comprise a plurality of staples  6220  and, in addition, an alignment matrix  6260  comprising a plurality of alignment guides, such as slots, grooves, and/or apertures, for example, which can be configured to align the staples  6220 . In various circumstances, the alignment matrix  6260  can be configured such that the staple legs  6221  of the staples  6220  are aligned with the retention apertures  6252  in the retention matrix  6250  before the retention matrix  6250  is engaged with the staple legs  6221 . In various embodiments, referring now to  FIGS. 117 and 118 , the alignment matrix  6260  can comprise a plurality of alignment apertures  6262  which can be configured to closely receive the staple legs  6221  of the staples  6220 . In at least one such embodiment, each staple  6220  can comprise a base  6222  and two staple legs  6221  extending from the base  6222  wherein the bases  6222  of the staples  6220  can extend around a bottom surface  6264  of the retention matrix  6260  and the staple legs  6221  can extend upwardly through the alignment apertures  6262 . In certain embodiments, each alignment aperture  6262  can be circular, or at least substantially circular, and can be defined by a diameter which is equal to or slightly larger than the diameter of the staple leg  6221  extending therethrough. In various embodiments, the alignment matrix  6260  can further comprise a plurality of raised members  6263  which can extend upwardly from the top surface  6261  of the alignment matrix  6260  and surround, or at least partially surround, the alignment apertures  6262 . In certain embodiments, the raised members  6263  can provide for longer alignment apertures  6262  wherein, in various circumstances, longer apertures  6262  can provide more control over the alignment of the staple legs  6221  than shorter apertures  6262 . 
     In use, in various embodiments, a first jaw supporting the staple cartridge  6200  can be positioned on one side of the tissue that is to be stapled and a second jaw supporting the retention matrix  6250  can be positioned on the other side of the tissue. Once the jaws have been suitably positioned relative to the tissue, in certain embodiments, the second jaw and the retention matrix  6250  can be moved toward the staple cartridge  6200 . As the staple legs  6221  are being inserted through the retention apertures  6252  of the retention matrix  6250 , in various embodiments, a tissue-contacting, or bottom, surface  6251  of the retention matrix  6250  can contact the tissue and press the tissue against the tissue-contacting, or top, surface  6261  of the alignment matrix  6260 . In various other embodiments, as described in greater detail further below, the staple cartridge  6200  can further comprise a compressible cartridge body positioned above the top surface  6261  of the alignment matrix  6260 , for example, which can contact the tissue. In certain embodiments, referring again to  FIGS. 114 and 118 , the alignment matrix  6260  can further comprise one or more apertures  6203  defined therein which, when the alignment matrix  6260  is positioned against tissue, can be configured to receive a portion of the tissue therein. In embodiments where a compressible cartridge body is positioned above and/or against the alignment matrix  6260 , a portion of the compressible cartridge body can enter into the apertures  6203  when the cartridge body is compressed. Similarly, the retention matrix  6250  can comprise a plurality of apertures  6202  which can be configured to receive at least a portion of the tissue therein when the retention matrix  6250  is positioned against the tissue. 
     As the staple legs  6221  of the staples  6220  are inserted through the retention apertures  6252  of the retention matrix  6250 , further to the above, the tips of the staple legs  6221  may protrude upwardly from the top surface  6257  of the retention matrix  6250 . In various circumstances, as described above, the tips of the staple legs  6221  may remain unbent after they have been inserted through the retention apertures  6252 . In certain embodiments, referring now to  FIGS. 121-124 , a fastening system comprising the staple cartridge  6200  and the retention matrix  6250  may further comprise a plurality of protective caps or covers, such as caps  6270 , for example, which can be assembled to the staple legs  6221  protruding above the retention matrix  6250 . In various embodiments, each cap  6270  can entirely, or at least partially, cover the sharp end of a staple leg  6221  such that the sharp end does not contact tissue positioned adjacent thereto. In at least one embodiment, referring now to  FIG. 124 , each cap  6270  can comprise an aperture  6271  defined therein which can be configured to closely receive a tip of a staple leg  6221  therein. In various embodiments, the caps  6270  can be comprised of an elastomeric material, such as silicone, polyisoprene, sanoprene, and/or natural rubber, for example. In at least one embodiment, the aperture  6271  can comprise a perimeter or diameter which is smaller than the perimeter or diameter of the staple leg  6221  inserted therein. In at least one such embodiment, the aperture  6271  in the protective cap  6270  can expand in order to receive the staple leg  6221  therein. In various alternative embodiments, the caps  6270  may not comprise apertures and the tips of the staple legs  6221  can be configured to incise the caps  6270  as the legs  6221  are inserted therein. In any event, in various embodiments, each cap  6270  can be seated onto a staple leg  6221  until the base  6272  of the cap  6270  abuts, or is positioned adjacent to, the top surface  6257  of the retention matrix  6250 . In various circumstances, the caps  6270  can be configured such that they are seated snugly onto the tips of the staple legs  6221  such that they are not easily removed therefrom. In certain embodiments, each cap  6270  can comprise a conical, or at least substantially conical, outer surface, for example. In various embodiments, the caps  6270  can comprise any suitable shape, such as shapes comprising a parabolic, or at least substantially parabolic, outer surface, for example. 
     In various embodiments, the fastener system described above, for example, could be deployed using the surgical stapler depicted in  FIGS. 125-127 , for example. In various embodiments, the end effector can comprise a first jaw, or staple cartridge channel,  6230  which can be configured to support the staple cartridge  6200  therein and a second jaw  6240  which can be configured to support the retention matrix  6250  and the plurality of protective caps  6270 . Referring primarily to  FIG. 125 , which illustrates the second jaw  6240  in an open configuration, the jaws  6230  and  6240  can be positioned relative to tissue T such that the tissue T is positioned intermediate the retention matrix  6250  and the staple cartridge  6200 . In various embodiments, as discussed above, the staple cartridge  6200  can further comprise a compressible cartridge body, such as cartridge body  6210 , for example, in which the staples  6220  and the alignment matrix  6260  can be positioned. In at least one such embodiment, the tissue T can be positioned against a top surface of the cartridge body  6210 . In certain embodiments, the second jaw  6240  can comprise a plurality of recesses, or apertures,  6245  configured to receive the plurality of protective caps  6270  and, in addition, one or more retention features, or retainers, which can be configured to hold the retention matrix  6250  in position over the caps  6270 . In at least one such embodiment, the retention matrix  6250  can be configured to retain the caps  6270  in the apertures  6245 . In various embodiments, referring now to  FIG. 137 , each aperture  6245  can be configured to receive a portion of, or the entirety of, a cap  6270  therein. In certain embodiments, the apertures  6245  can be sufficiently sized and configured such that the caps  6270  can be secured therein by at least one of a press-fit and/or snap fit arrangement, for example. In some embodiments, at least one adhesive could be utilized to secure the caps  6270  in the apertures  6245 . In at least one such embodiment, such an adhesive could be selected such that caps  6270  can detach from the second jaw  6240  after the caps  6270  have been engaged with the staple legs  6221  and the second jaw  6240  is moved away from the implanted fastener assembly. In certain embodiments, referring now to  FIG. 138 , the second jaw  6240  can further comprise at least one cover sheet  6246  which can be assembled to the second jaw  6240  and can extend over and retain the caps  6270  in the apertures  6245 . In at least one such embodiment, at least a portion of the cover sheet  6246  can be secured to the jaw  6240  utilizing at least one adhesive, for example. In use, in at least one embodiment, the cover sheet  6246  can be at least partially detached from the jaw  6240  before the end effector is inserted into a surgical site. In certain embodiments, the cover sheet  6246  can be comprised of an implantable material, such as PDS and/or PGA, for example, which can be incised by the staple legs  6221  as the staple legs  6221  emerge from the retention matrix  6250 . In at least one such embodiment, the cover sheet  6246  can be secured in the fastening system intermediate the covers  6270  and the retention matrix  6250 . 
     Further to the above, referring now to  FIG. 126 , the jaw  6240  can be moved from an open position to a closed position in which the tissue T is positioned against the retention matrix  6250  and the cartridge body  6210 . In such a position, the retention matrix  6250  may not yet be engaged with the staples  6220 . In various embodiments, the jaw  6240  can be moved between its open position and its closed position by an actuator  6235 . In at least one such embodiment, the jaw  6240  can comprise a distal pin  6243  and a proximal pin  6244  extending therefrom, wherein the distal pin  6243  can slide vertically, or at least substantially vertically, within a distal slot  6233  defined in the cartridge channel  6230 , and wherein the proximal pin  6244  can slide vertically, or at least substantially vertically, within a proximal slot  6234  which is also defined in the staple cartridge channel  6230 . In use, the actuator  6235  can be retracted proximally in order to drive the pins  6243  and  6244  into the upper ends of their respective slots  6233  and  6234  as illustrated in  FIG. 126 . In at least one such embodiment, the actuator  6235  can comprise a distal drive slot  6236  and a proximal drive slot  6237 , wherein the sidewalls of the drive slots  6236  and  6237  can be configured to contact the distal pin  6243  and the proximal pin  6244 , respectively, and drive the pins  6243  and  6244  upwardly as the actuator  6235  is moved proximally. More particularly, as the actuator  6235  is moved proximally, the distal pin  6243  can slide up an inclined first portion  6236   a  of the distal drive slot  6236  into an intermediate, or second, portion  6236   b  and, similarly, the proximal pin  6244  can slide up an inclined first portion  6237   a  of the distal drive slot  6237  into an intermediate, or second, portion  6237   b . As the pins  6243  and  6244  are both moved upwardly, the jaw  6240  can be rotated downwardly toward the tissue T into a closed position. 
     Further to the above, referring now to  FIG. 127 , the actuator  6235  can be pulled further proximally in order to push the second jaw  6240  downwardly toward the first jaw  6230 , compress the cartridge body  6210 , and engage the retention matrix  6250  and the plurality of protective caps  6270  with the staple legs of the staples  6220 . In at least one such embodiment, the additional proximal movement of the actuator  6235  can cause the sidewalls of the drive slots  6236  and  6237  to contact the pins  6243  and  6244 , respectively, and drive the pins  6243  and  6244  downwardly toward the bottom ends of the slots  6233  and  6234 , respectively. In such circumstances, the actuator  6235  can be pulled proximally such that, one, the distal pin  6243  exits the second portion  6236   b  of the drive slot  6236  and enters into an inclined third portion  6236   c  and, similarly, the proximal pin  6244  exits the second portion  6237   b  of the drive slot  6237  and enters into an inclined third portion  6237   c . As the pins  6243  and  6244  are both moved downwardly, the second jaw  6240  can move downwardly toward the first jaw  6230  into a fired position. In at least one such embodiment, the second jaw  6240  can be moved downwardly such that the retention matrix  6250  remains parallel, or at least substantially parallel, to the top surface of the cartridge body  6210  and/or parallel, or at least substantially parallel, to the alignment matrix  6260 . In any event, once the retention matrix  6250  and the protective caps  6270  have been engaged with the staple legs  6221  of the staples  6220 , as illustrated in  FIG. 129 , the second jaw  6240  can be returned to an open, or an at least substantially open, position. In at least one such embodiment, the actuator  6235  can be pushed distally in order to drive the pins  6243  and  6244  to the top ends of the slots  6233  and  6234 , respectively, and then driven downwardly toward the bottom ends of the slots  6233  and  6234  once the pins have passed through the intermediate portions  6236   b  and  6237   b  of the respective drive slots  6236  and  6237 . Once the second jaw  6240  has been opened, the first jaw  6230  can be detached from the implanted staple cartridge  6200  and the first and second jaws  6230 ,  6240  can be removed away from the implanted fastener assembly, as illustrated in  FIG. 128 . 
     Referring to  FIG. 127  once again, the reader will note that the pins  6243  and  6244  are not illustrated as being seated in the very bottoms of their respective slots  6233  and  6234  eventhough the retention matrix  6250  and the caps  6270  have been engaged with the staple legs  6221 . Such circumstances can arise when thick tissue T is positioned between the retention matrix  6250  and the cartridge body  6210 . In circumstances where thinner tissue T is positioned between the retention matrix  6250  and the cartridge body  6210 , referring now to  FIG. 130 , the pins  6243  and  6244  can be drive further downwardly into their respective slots  6233  and  6234  as illustrated in  FIG. 132 . In general, in at least one such embodiment, the actuator  6235  can be pulled proximally in order to drive the pins  6243  and  6244  upwardly and downwardly through the progressions described above and illustrated in  FIGS. 130-132  and, owing to the thinner tissue T, the retention matrix  6250  and the protective caps  6270  can be driven further onto the staple legs  6221  of the staples  6220 , as illustrated in  FIGS. 133 and 134 . In various embodiments, as a result of the adjustability afforded by the retention matrix  6250 , the same, or at least substantially the same, compressive pressure can be obtained in the fastened tissue regardless of whether the tissue captured within the end effector is thick or thin. In certain embodiments, the adjustability afforded by the retention matrix  6250  can allow a surgeon can select whether to apply a larger compressive pressure or a smaller compressive pressure to the tissue by selecting the depth to which the retention matrix  6250  is seated. In at least one such embodiment, the range in which the retention matrix  6250  can be seated onto the staple legs  6221  can be determined by the lengths, or ranges, of the slots  6233  and  6234 , for example. 
     In various embodiments, as described above, the protective caps  6270  can be comprised of a soft or flexible material, for example, which can be configured to grip the ends of the staple legs  6221 . In certain embodiments, the protective caps  6270  can be comprised of a bioabsorbable plastic, polyglycolic acid (PGA) which is marketed under the trade name Vicryl, polylactic acid (PLA or PLLA), polydioxanone (PDS), polyhydroxyalkanoate (PHA), poliglecaprone 25 (PGCL) which is marketed under the trade name Monocryl, polycaprolactone (PCL), and/or a composite of PGA, PLA, PDS, PHA, PGCL and/or PCL, for example, and/or a biocompatible metal, such as titanium and/or stainless steel, for example. As illustrated in  FIG. 124 , in at least one embodiment, each cap  6270  can be unconnected to the other caps  6270 . In certain other embodiments, one or more caps  6270  can be mounted to the retention matrix  6250 . In at least one such embodiment, the caps  6270  can be connected to the retention matrix  6250  by at least one adhesive, for example, wherein the apertures  6271  in the caps  6270  can be aligned, or at least substantially aligned, with the retention apertures  6252  in the retention matrix  6270 . In various embodiments, referring now to  FIG. 135 , a protective cap, such as a cap  6370 , for example, can define an inner cavity, or dome,  6374  which can be configured to receive a tip of a staple leg  6221 , for example, therein. In at least one such embodiment, the cap  6370  can comprise a bottom  6372  and an aperture  6371  extending through the bottom  6372 . In various embodiments, the aperture  6371  can be defined by one or more deflectable members  6373  which can be configured to deflect when the staple leg  6221  is inserted therethrough. In certain embodiments, two or more caps  6370 , for example, can be connected together to form an array of caps  6370 . In at least one such embodiment, referring now to  FIG. 136 , a plurality of caps  6370  can be connected together by a sheet of material  6375 . In certain embodiments, the sheet  6375  can be sufficiently rigid in order to maintain a desired arrangement and/or alignment of the caps  6370 . In at least one embodiment, the caps  6370  can be comprised of a biocompatible metal, such as titanium and/or stainless steel, for example, and the sheet  6375  can be comprised of a bioabsorbable plastic, polyglycolic acid (PGA) which is marketed under the trade name Vicryl, polylactic acid (PLA or PLLA), polydioxanone (PDS), polyhydroxyalkanoate (PHA), poliglecaprone 25 (PGCL) which is marketed under the trade name Monocryl, polycaprolactone (PCL), and/or a composite of PGA, PLA, PDS, PHA, PGCL and/or PCL, for example. In various embodiments, a sheet  6375  can be comprised of a bioabsorbable material including an anti-microbial agent, such as colloidal silver and/or triclosan, for example, stored and/or dispersed therein which can be released as the sheet  6375  is bioabsorbed, for example. 
     In various embodiments, further to the above, the sheet  6375  can be injection molded around the caps  6370  utilizing an injection molding process, for example, such that the caps  6370  are embedded in the sheet  6375 . In certain other embodiments, the sheet  6375  can be molded utilizing an injection molding process, for example, wherein apertures  6376  can be formed in the sheet  6375  during the injection molding process and/or after the injection molding process utilizing a stamping process, for example. In either event, the caps  6370  can be inserted into and secured in the apertures  6376  utilizing a press-fit and/or snap-fit interconnection and/or at least one adhesive. In certain embodiments, each cap  6370  can comprise an annular groove surrounding, or at least partially surrounding, the perimeter of the cap  6370  which can be configured to receive the perimeter of an aperture  6376  therein. In certain embodiments, the sheet  6375  can be comprised of a flexible and/or pliable material which can permit relative movement between the caps  6370 . In at least one such embodiment, the flexible sheet  6375  can be comprised of a rubber, plastic, and/or silicone material, for example, and the caps  6370  can be comprised of a rigid material, such as metal, for example. In at least one such embodiment, similar to the above, the flexible material can be molded around the caps  6370 . In certain embodiments, the caps  6370  can be pressed into a pre-molded sheet  6375 , for example. In various embodiments, the durometer of the flexible material can be selected to provide a desired stiffness of the sheet  6375 . In certain embodiments, the sheet  6375  can be configured such that it comprises a flexible band. In any event, the sheet  6375  can facilitate the assembly of the caps  6370  into an end effector as a plurality of the caps  6370  can be positioned and/or aligned simultaneously within the end effector. Furthermore, the sheet  6375  connecting the caps  6370 , once implanted, can strengthen or bolster the tissue along the staple line, for example. In addition to or in lieu of a sheet connecting the caps  6370 , the caps  6370  can be connected together by a plurality of links. In at least one such embodiment, such links can be flexible and can permit relative movement between the caps  6370 . 
     In various embodiments, referring now to  FIGS. 139 and 140 , a protective cap, such as cap  6470 , for example, can comprise a forming surface which can be configured to deform a tip of a staple leg. In at least one such embodiment, the cap  6470  can comprise a base  6472  which can include an aperture  6471  extending therethrough. In various embodiments, the aperture  6471  can be configured to closely receive a staple leg, such as a staple leg  6221 , for example, therein. In at least one embodiment, the aperture  6471  can be defined by a diameter or perimeter which can be equal to or larger than the diameter or perimeter of the staple leg  6221 . In various embodiments, the cap  6470  can further comprise a cavity, or dome,  6474  which can be configured to receive the tip of the staple leg  6221  as it is inserted into the cap  6470 . Referring primarily to  FIG. 140 , the cap  6470  can further comprise an anvil, or forming surface,  6473  which can be configured to deflect and deform the staple leg  6221 . In various circumstances, the forming surface  6473  can be curved and/or concave, for example, and can be configured to curl the staple leg  6221  as it is inserted into the cap  6470 . In certain embodiments, the staple leg  6221  can be sufficiently deformed such that it cannot be withdrawn through the aperture  6471  and, as a result, the cap  6470  can become locked to the staple leg  6221 . In at least one such embodiment, the base  6472  of the cap  6470  can define a lip extending around the aperture  6471  which can prevent the deformed staple leg  6221  from being removed from the cavity  6474 . In various circumstances, as a result of the above, one or more caps  6470  can prevent, or inhibit, a retention matrix, such as retention matrix  6250 , for example, from backing up or being disengaged from the staples  6220 . In various embodiments, although not illustrated, the cap  6470  can be symmetrically, or at least substantially symmetrically, formed, and the aperture  6471  can be located along a central axis  6479  extending through the cap  6470 . In various alternative embodiments, referring again to  FIG. 139 , the aperture  6471  can be offset with respect to the central axis  6479 . In at least one such embodiment, the offset aperture  6471  can allow the staple leg  6221  to contact a side of the forming surface  6473  and curl over to the other side of the forming surface  6473  instead of contacting the center of the forming surface  6473 , as may occur in embodiments comprising a centered aperture  6471  mentioned above. 
     In various embodiments, as discussed above, a retention matrix, such as retention matrix  6250 , for example, can be comprised of a sheet of material and a plurality of retention apertures  6252  extending therethrough. In at least some embodiments, the sheet of material comprising the retention matrix  6250  can be rigid or substantially inflexible. In certain other embodiments, a retention matrix can be comprised of an array of retention matrix elements and a plurality of flexible connectors, or links, connecting the retention matrix elements. In various embodiments, referring now to  FIG. 141 , a retention matrix, or a portion of retention matrix,  6550  can comprise a plurality of element bodies  6505  which can be connected together by one or more connecting links  6507 . In at least one embodiment, each element body  6505  can comprise a plurality of deformable members  6553  which define a retention aperture  6552  therein. In certain embodiments, the element bodies  6505  and the connecting links  6507  of a retention matrix  6550  can be integrally formed and can comprise a unitary piece of material. In various embodiments, the retention matrix  6550  can be stamped or cast, for example, from a metal material, such as titanium and/or stainless steel, for example. In at least one embodiment, the retention matrix  6550  can be comprised of plastic, such as polyetheretherketone (PEEK), polypropylene which is marketed under the trade name Prolene, polyester, polyethylene terephthalate which is marketed under the trade names Ethibond and Mersilene, polyvinylidene fluoride, polyvinylidene fluoride-co-hexafluoropropylene, poly hexafluoropropylene-VDF which is marketed under the trade name Pronova, and/or long-chain aliphatic polymers Nylon 6 and Nylon 6,6 which are marketed under the trade names Ethilon &amp; Nurolon, for example, and can be formed by an injection molding process, for example. In certain embodiments, the element bodies  6505  may not be integrally formed with the connecting links  6507 . In various embodiments, a plurality of singular element bodies  6505  can be produced which are subsequently connected together and embedded in a retention matrix. In at least one such embodiment, the element bodies  6505  can be stamped from a metal material, such as titanium and/or stainless steel, for example, and placed in a plastic injection mold wherein a plastic material can be injected into the mold to form, one, a rim  6506  of material surrounding, or at least partially surrounding, the element bodies  6505  and, two, connecting links  6507  extending from the rims  6506 . In certain other embodiments, one or more connector lattices can be formed comprising apertures defined within a plurality of rims  6506  wherein each such aperture can be configured to receive an element body  6505  therein. In at least one embodiment, each element body  6505  can comprise a circular, or at least substantially circular, outer perimeter and, similarly, each rim  6506  can define a circular, or at least substantially circular, aperture therein, wherein the diameter of the aperture can be equal to or smaller than the diameter of the element body  6505 . In at least one such embodiment, the element bodies  6505  can be press-fit or embedded into the apertures in the rims  6505 . In certain embodiments, the element bodies  6505  can be secured in the apertures utilizing at least one adhesive. 
     In various embodiments, further to the above, a retention matrix can comprise a plurality of element bodies  6505  and a plurality of connecting links  6507  which can connect the element bodies  6505  in any suitable array, such as those illustrated in  FIGS. 142-145 , for example. Regardless of the pattern of the array, in various embodiments, the connecting links  6507  can be configured to allow the element bodies  6505  and the retention apertures  6552  to move relative to one another. In at least one such embodiment, the lattice of element bodies  6505  and connecting links  6507  comprising the retention matrix  6550 , once engaged with tissue, can be configured to stretch, twist, contract, and/or otherwise flex in order to permit at least some movement within the tissue yet, at the same time, resist larger movements thereof. In various embodiments, each connecting link  6507  can comprise a flexible member configured to stretch, twist, and/or contract in order to permit the retention matrix  6550  to flex intermediate the matrix retention elements  6505 , for example. Referring again to  FIG. 141 , each link  6507  extending from a rim  6506  can be defined by a width which is narrower than the width of the element body  6505  and/or the rim  6506 . In certain embodiments, referring to  FIGS. 142-145 , one or more links  6507  can comprise straight portions which extend along a line between adjacent element bodies  6506 , for example. In at least one such embodiment, each link  6507  can comprise a first end attached to a first rim  6506  and a second end attached to a second rim  6506 . In certain embodiments, referring once again to  FIG. 141 , two or more links  6507  can be connected to one another. In at least one such embodiment, two or more links  6507  can be connected at an intermediate hinge  6509 , for example. In various embodiments, the hinge  6509  can comprise a reduction in cross-sectional thickness in one or more directions as compared to the cross-sectional thickness of the links  6507  which can permit the connected links  6507  to move relative to each other, for example. In certain embodiments, the retention matrix  6550  can further comprise hinges  6508  which can connect the links  6507  to the rims  6506  and permit relative movement between the links  6507  and the rims  6506 . Similar to hinges  6509 , hinges  6508  can comprise a reduction in cross-sectional thickness in one or more directions as compared to the cross-sectional thickness of the links  6507 , for example. 
     In various embodiments, further to the above, the connected links  6507  can extend in different directions. In at least one such embodiment, a first link  6507  can extend in a first direction and a second link  6507  can extend in a second direction, wherein the first direction can be different than the second direction. In certain embodiments, the first link  6507  can extend along a first line and the second link  6507  can extend along a second line, wherein the first line and the second line can intersect each other at an angle, such as approximately 30 degrees, approximately 45 degrees, approximately 60 degrees, and/or approximately 90 degrees, for example. In various embodiments, the hinges  6508  and/or hinges  6509  can comprise living hinges which can permit the links  6507  to move relative to each other a number of times without breaking. In certain embodiments, the hinges  6508  and/or hinges  6509  can comprise frangible, or easily-breakable, portions which can break when flexed too far and/or flexed too many times. In at least one such embodiment, such frangible portions can permit one or more portions of the retention matrix  6550  to break away from another portion of the retention matrix  6550 . In various embodiments, the hinges  6508  and/or hinges  6509 , for example, can comprise sections of the retention matrix  6550  which are easier to incise than the other portions of the retention matrix  6550 . More particularly, an implanted retention matrix, and the tissue fastened by the implanted retention matrix, may oftentimes by incised by a cutting member for various reasons and, in order to facilitate such cross-cutting, the hinges  6508  and/or hinges  6509  can provide avenues, or thin sections, through which a cutting member can more easily pass through the retention matrix  6550 , for example. In various embodiments, further to the above, the connecting links  6507  can comprise one or more coined features or material upsets, for example, defined therein which can facilitate the bending, breakage, and/or incision of the connecting links  6507 . 
     In various embodiments, a retention matrix can comprise a plurality of retention matrix elements, such as matrix element bodies  6505 , for example, which can be embedded in a flexible sheet, or band, of material. In at least one embodiment, a flexible sheet of material can be formed from a bioabsorbable, elastomeric material, such as silicone, for example, wherein the flexible sheet can be produced with a plurality of apertures defined therein. In at least one such embodiment, a solid flexible sheet can be molded and a plurality of apertures can be punched out of the flexible sheet. In various alternative embodiments, the flexible sheet can be molded and the apertures defined therein can be formed during the molding process. In either event, the retention matrix elements  6505 , for example, can be inserted into and retained within the flexible sheet. In certain other embodiments, similar to the above, the flexible sheet can be formed around the matrix elements  6505 . In at least one embodiment, the flexible sheet can be comprised of a woven mesh, for example, and/or any other suitable material. Such a woven mesh, further to the above, may be easy to cross-cut. 
     In various embodiments, referring now to  FIGS. 146 and 147 , a fastener system comprising a retention matrix, such as retention matrix  6250 , for example, can further comprise a cover, such as cover  6670 , for example, which can cover the tips of the staple legs  6221  when they extend above the top surface  6257  of the retention matrix  6250 . In various embodiments, the cover  6670  can be attached to the retention matrix  6250 . In certain embodiments, the cover  6670  and/or the retention matrix  6250  can comprise retention features which can be configured to retain the cover  6670  to the retention matrix  6250 . In at least one embodiment, at least one adhesive can be utilized to adhere the cover  6670  to the retention matrix  6250 . In at least one embodiment, the cover  6670  can be comprised of a single layer, although the cover  6670  is illustrated as comprising two layers as described in greater detail further below. In various embodiments, referring primarily to  FIG. 147 , the tips of the staple legs  6221  can extend through a bottom surface  6673  of the cover  6670 ; however, the cover  6670  can comprise a sufficient thickness such that the staple tips do not extend through the top surface  6675  of the cover  6670 . In at least one such embodiment, as a result, the tips of the staple legs  6221  may not protrude from the cover  6670 . In various embodiments, the cover  6670  can comprise a plurality of layers. In at least one such embodiment, the cover  6670  can comprise a first layer  6671  and a second layer  6672 . In at least one embodiment, the first layer  6671  and the second layer  6672  can be attached to one another wherein, in at least one embodiment, the second layer  6672  can comprise a bottom surface  6676  which is adhered to the first layer  6671 . In various embodiments, the first layer  6671  and the second layer  6672  can comprise different thicknesses while, in certain embodiments, they can comprise the same thickness. In at least one embodiment, the first layer  6671  and the second layer  6672  can comprise substantially the same width and/or length. In alternative embodiments, the layers  6671  and  6672  can comprise different widths and/or lengths. 
     In various embodiments, further to the above, the first layer  6671  can be comprised of a compressible foam, mesh material, and/or hydrogel, for example, which can be incised by the staple legs  6211 . In at least one embodiment, the second layer  6672  can be comprise of a tougher material, or skin, such as PGA and/or PDS, for example, and/or any suitable buttress material. In at least one such embodiment, the staple legs  6221  can be configured to penetrate the first layer  6671 ; however, in various embodiments, the staple legs  6221  may be unable to penetrate the second layer  6672 . In certain embodiments, the second layer  6672  can be comprised of a material having a sufficient resiliency and/or toughness which can permit the second layer  6672  to be contacted and displaced by the staple leg  6221  but not be incised, or only marginally incised, by the staple tip of the staple leg  6221 . Although not illustrated, a cover can comprise more than two layers wherein one or more of such layers may be penetration-resistant. In use, in at least one such embodiment, the retention matrix  6250  can be positioned against the tissue to be fastened and pushed downwardly such that the staple legs  6221  of the staples  6220  are pushed through the tissue T and the retention apertures  6252  in the retention matrix  6250  and enter into the first layer  6271  of the cover  6270 . In various embodiments, the tips of the staple legs  6221  may not enter, or at least substantially enter, into the second layer  6272  of the cover  6270 . After the retention matrix  6250  has been suitably positioned, the jaw  6240  can be opened and the cover  6670  and the retention matrix  6250  can detach from the jaw  6240  as illustrated in  FIG. 146 . As illustrated in  FIG. 146 , a jaw  6640  can be configured to hold more than one retention matrix  6250  and cover  6670 . In at least one such embodiment, the jaw  6640  can comprise two channels  6679  which each can be configured to receive a cover  6670  therein and a retention matrix  6250  positioned thereover such that the tissue-contacting surface  6251  of each retention matrix  6250  depends downwardly from the bottom of the jaw  6240 . In at least one such embodiment, a retention matrix  6250  and a cover  6270  can be housed in the jaw  6640  on each side of a knife slot  6678 . In use, both retention matrices  6250  and covers  6670  can be deployed simultaneously and/or to the same depth with respect to opposing staple cartridges, such as cartridges  6200 , for example, positioned thereacross. Thereafter, in various embodiments, the fastened tissue can be incised along a cutting line by a cutting member that traverses the knife slot  6678  wherein the jaw  6640  can then be re-opened. In certain embodiments, the covers  6670  may not be attached to the retention matrix  6250 . In at least one such embodiment, the covers  6670  can be positioned in the channels  6679  and can be retained in the channels  6679  by the retention matrices  6250  which can be secured to the jaw  6640 . In various embodiments, the each retention matrix  6250  can be wider and/or longer than their respective covers  6670  such that the retention matrices  6250  can retain the entirety of their covers  6670  in position. In certain embodiments, each retention matrix  6250  can comprise the same width and/or length as their respective cover  6670 , for example. 
     In various embodiments, as described above, a fastener system can comprise a layer of material which can be attached to a retention matrix, such as retention matrix  6250 , for example. In at least one embodiment, referring now to  FIG. 150 , a layer of material  6870  can be attached to the bottom surface  6251  of the retention matrix  6250 . In certain embodiments, the layer  6870  and/or the retention matrix  6250  can comprise retention features which can be configured to retain the layer  6870  to the retention matrix  6250 . In at least one embodiment, at least one adhesive can be utilized to adhere the layer  6870  to the retention matrix  6250 . In any event, the layer  6870  can comprise a bottom, or tissue-contacting, surface  6873  which can be configured to contact the tissue T when the retention matrix  6250  is moved downwardly toward the staples  6220  to engage the retention apertures  6252  with the staple legs  6221 . In at least one such embodiment, the layer  6870  can be comprised of a compressible material, such as a bioabsorbable foam, for example, which can be compressed between the bottom surface  6251  of the retention matrix  6250  and the tissue T. In various embodiments, the layer  6870  can further comprise at least one medicament stored and/or absorbed therein which can be expressed from the layer  6870  as the layer  6870  is compressed. In at least one embodiment, the medicament can comprise at least one tissue sealant, haemostatic agent, and/or anti-microbial material, such as ionized silver and/or triclosan, for example. In various embodiments, the compression of the layer  6870  can squeeze the medicament from the layer  6870  such that the entirety of, or at least a significant portion of, the surface of the tissue T is covered with the medicament. Furthermore, as the layer  6870  is compressed and the staple legs  6221  penetrate the tissue T and the layer  6870 , the medicament can flow down the staple legs  6221  and treat the tissue that has just been incised by the staple legs  6221 , for example. In various embodiments, the body of the retention matrix  6250  can comprise a first layer which is comprised of a biocompatible material, such as titanium and/or stainless steel, for example, and the bottom layer  6870  can comprise a second layer comprised of a bioabsorbable material, such as oxidized regenerated cellulose (ORC), biologically active agents like fibrin and/or thrombin (either in their liquid state or freeze dried), glycerin, absorbable porcine gelatin in either flue or foam configurations, and/or anti-microbials, such as ionized silver and/or triclosan, for example. Additional bioabsorbable materials can comprise Surgicel Nu-Knit, Surgicel Fibrillar, collagen/ORC which is a hybrid with a built in collagen matrix and is marketed under the trade name Promogran, polyglycolic acid (PGA) which is marketed under the trade name Vicryl, polylactic acid (PLA or PLLA), polydioxanone (PDS), polyhydroxyalkanoate (PHA), poliglecaprone 25 (PGCL) which is marketed under the trade name Monocryl, polycaprolactone (PCL), and/or a composite of PGA, PLA, PDS, PHA, PGCL and/or PCL, for example. Although only one layer  6870  is illustrated in  FIG. 150 , any suitable number of layers could be used. In at least one embodiment, a first layer comprising a first medicament could be attached to the retention matrix  6250  and a second layer comprising a second, or different, medicament could be attached to the first layer. In at least one such embodiment, a plurality of layers could be used wherein each layer can comprise a different medicament and/or a different combination of medicaments contained therein. 
     In various embodiments, referring now to  FIG. 148 , a fastener system can comprise a layer of material  6770  attached to the bottom surface  6251  of the retention matrix  6250 . In certain embodiments, the layer  6770  and/or the retention matrix  6250  can comprise retention features which can be configured to retain the layer  6770  to the retention matrix  6250 . In at least one embodiment, at least one adhesive can be utilized to adhere the layer  6770  to the retention matrix  6250 . In any event, the layer  6770  can comprise a bottom, or tissue-contacting, surface  6773  which can be configured to contact the tissue T when the retention matrix  6250  is moved downwardly toward the staples  6220  to engage the retention apertures  6252  with the staple legs  6221 . In at least one such embodiment, the layer  6770  can be comprised of a compressible material, such as a bioabsorbable foam, for example, which can be compressed between the surface  6251  of the retention matrix  6250  and the tissue T. In various embodiments, the layer  6770  can further comprise one or more encapsulations, or cells,  6774  which can be configured to store at least one medicament therein. In certain embodiments, referring to  FIG. 149 , the encapsulations  6774  can be aligned, or at least substantially aligned, with the retention apertures  6252  such that, when the staple legs  6221  are pushed through the tissue T and the layer  6770 , the staple legs  6221  can puncture and/or otherwise rupture the encapsulations  6774 . After the encapsulations  6774  have been ruptured, the at least one medicament M stored in the encapsulations  6774  can flow out onto the tissue T. In at least one such embodiment, the medicament M can comprise a fluid which can flow or wick down the staple legs  6221  and treat the tissue T that was just incised by the staple legs. As a result of the above, the medicament stored within the encapsulations  6774  can provide a localized treatment to the tissue. In certain embodiments, the encapsulations  6774  in the sheet  6770  can comprise different medicaments stored therein. For example, a first group of encapsulations  6774  can comprise a first medicament, or a first combination of medicaments, stored therein and a second group of encapsulations can comprise a different medicament, or a different combination of medicaments, stored therein. In various embodiments, the layer  6770  can be comprised of a flexible silicone sheet and the encapsulations  6774  can represent voids in the silicone sheet. In at least one such embodiment, the silicone sheet can comprise two layers that can be attached to one another wherein the encapsulations  6774  can be defined between the two layers. In various embodiments, the layer  6770  can comprise one or more thin sections or weakened portions, such as partial perforations, for example, which can facilitate the incision of the layer  6770  and the rupture of the encapsulations  6774  by the legs  6221 . In certain embodiments, at least a portion of the encapsulations  6774  can be positioned within domes  6777 , wherein the domes  6777  can extend upwardly from the sheet  6770 . In at least one such embodiment, the domes  6777  and/or at least a portion of the encapsulations  6774  can be positioned within the pockets  6201  formed within the retention matrix  6250 . In certain embodiments, the encapsulations  6774  may comprise discrete cells which are unconnected to each other. In certain other embodiments, one or more of the encapsulations  6774  can be in fluid communication with each other via one or more passageways, conduits, and/or channels, for example, extending through the layer  6770 . The disclosure of U.S. Pat. No. 7,780,685, entitled ADHESIVE AND MECHANICAL FASTENER, which issued on Aug. 24, 2010, is hereby incorporated by reference in its entirety. 
     In various embodiments, further to the above, a staple cartridge comprising a cartridge body, staples, and/or an alignment matrix therein can be loaded into a first jaw of an end effector and, similarly, a retention matrix and/or one or more covers can be loaded into a second jaw of the end effector. In certain embodiments, referring now to  FIG. 151 , an instrument, such as cartridge loader  6990 , for example, can be used to insert two or more fastener cartridges into an end effector at the same. In at least one embodiment, the cartridge loader  6990  can comprise a handle  6991  and a cartridge carrier  6992 , wherein the cartridge carrier  6992  can comprise a first retention portion configured to retain the cartridge body  6210  of the staple cartridge  6200  thereto and, in addition, a second retention portion configured to retain a cartridge body  6980  which supports, one, a plurality of protective caps  6270  therein and, two, a retention matrix  6250  along the bottom surface thereof, for example. In various embodiments, the first and second retention portions can each comprise one or more retention members configured to releasably engage the cartridge bodies  6210  and  6980 . In use, referring now to  FIGS. 152 and 153 , an end effector can comprise a first, or bottom, jaw  6230  and a second, or top, jaw  6940 , wherein the staple cartridge  6200  can be loaded into the first jaw  6230  and the cartridge body  6980  can be loaded into the second jaw  6940 . In various circumstances, the top jaw  6940  can be rotated from an open position ( FIG. 152 ) to a closed position ( FIG. 153 ) by an actuator  6235 , wherein the operation of the actuator  6235  is described above and is not repeated herein for the sake of brevity. Once the top jaw  6940  is in its closed position, referring now to  FIG. 153 , the distal end  6993  of the cartridge carrier  6992  can be inserted into the end effector such that the staple cartridge  6200  is slid through the distal end  6938  of the first jaw  6930  and into a first attachment portion, or channel,  6939  in the first jaw  6230 . Similarly, the distal end  6993  of the cartridge carrier  6992  can be inserted into the end effector such that the cartridge body  6980  is slid through the distal end  6948  of the second jaw  6940  and into a second attachment portion, or channel,  6949  in the second jaw  6940 . A surgeon, or other clinician, holding the handle  6991  of the cartridge loader  6990  can push the staple cartridge  6200  and the cartridge body  6980  through the channels  6939  and  6949 , respectively, until the staple cartridge  6200  and the cartridge body  6980  are fully seated therein. 
     As the staple cartridge  6200  and the cartridge body  6980  are being seated, the staple cartridge  6200  and the cartridge body  6980  can each engage one or more retention portions in their respective jaws  6230  and  6940 , as described in greater detail further below. In any event, once the staple cartridge  6200  and the cartridge body  6980  have been seated, referring now to  FIG. 154 , the cartridge loader  6990  can be detached from the staple cartridge  6200  and the cartridge body  6980  and removed from the end effector. In at least one such embodiment, the retention force holding the staple cartridge  6200  in the first jaw  6230  can be greater than the retention force holding the staple cartridge  6200  to the cartridge carrier  6992  such that, as the cartridge carrier  6992  is pulled distally out of the end effector, the staple cartridge  6200  can remain behind in the first jaw  6230 . Similarly, the retention force holding the cartridge body  6980  in the second jaw  6940  can be greater than the retention force holding the cartridge body  6940  to the cartridge carrier  6992  such that, as the cartridge carrier  6992  is pulled distally out of the end effector, the cartridge body  6940  can remain behind in the second jaw  6940 . Once the cartridge loader  6990  has been removed from the end effector, the loaded first jaw  6230  and the loaded second jaw  6940  can be positioned relative to the tissue T that is to be stapled. Referring now to  FIG. 155 , the second jaw  6940  can be moved from an open position ( FIG. 154 ) to a fired position ( FIG. 155 ) in order to engage the retention matrix  6250  and the plurality of protective caps  6270  carried by the cartridge body  6980  with the staples  6220  positioned within the staple cartridge  6200 . 
     Referring now to  FIGS. 156 and 157 , the second jaw  6940  can be re-opened and the plurality of protective caps  6270  and the retention matrix  6250  can detach from the cartridge body  6980  such that the caps  6270  and the retention matrix  6250  can remain engaged with the tissue T and the staple cartridge  6200 . In at least one embodiment, the cartridge body  6980  can comprise a plurality of pockets in which the plurality of caps  6270  can be removably positioned and one or more retention slots configured to removably retain the retention matrix  6250  thereto. In various embodiments, the retention members of the second jaw  6940  engaged with the cartridge body  6980  can retain the cartridge body  6980  in the second jaw  6940  after the second jaw  6940  has been opened. In certain embodiments, the cartridge body  6980  can be configured to tear as the second jaw  6940  is opened such that a portion of the cartridge body  6980  is implanted with the caps  6270  and the retention matrix  6250  and a portion of the cartridge body  6980  remains in the second jaw  6940 . Similarly, referring again to  FIGS. 156 and 157 , the retention members of the first jaw  6230  engaged with the cartridge body  6210  can retain the cartridge body  6210  in the first jaw  6230  after the second jaw  6940  has been opened. In certain embodiments, the cartridge body  6210  can be configured to tear as the first jaw  6230  is pulled away from the implanted cartridge  6200  such that a portion of the cartridge body  6210  is implanted with the staples  6220  and alignment matrix  6260  and a portion of the cartridge body  6210  remains in the first jaw  6230 . In various embodiments, referring now to  FIGS. 158-160 , a staple cartridge, such as staple cartridge  6900 , for example, can comprise one or more longitudinal retention slots  6913  extending along the length of the cartridge body  6910  which, when the staple cartridge  6900  is inserted into a jaw  6930 , for example, can be configured to receive one or more longitudinal retention rails  6916  extending from the jaw  6930  therein. In use, in at least one embodiment, an end of the retention slots  6913  can be aligned with the distal ends of the retention rails  6916  before the staple cartridge  6900  is slid through the distal end  6938  of the retention channel  6939 , for example. 
     In various embodiments, referring again to  FIG. 160 , the jaw  6940  can comprise two retention channels  6949 , wherein each retention channel  6949  can be configured to receive a cartridge body  6980  comprising a plurality of caps  6270  and a retention matrix  6250  therein. In certain embodiments, each cartridge body  6980  can comprise one or more longitudinal retention shoulders  6917  which can be configured to be slid along one or more longitudinal retention rails  6918  of the second jaw  6940  as the cartridge bodies  6980  are inserted into their respective retention channels  6949  in jaw  6940 . In various embodiments, the retention rails  6918  and the retention shoulders  6917  can co-operate to retain the cartridge body  6980  in the second jaw  6940  as the cartridge bodies  6980  are detached from the caps  6270  and the retention matrix  6250  stored therein. In various embodiments, referring now to  FIG. 159 , the second jaw  6940  can further comprise one or more distal bumps, or retention members,  6915  extending therefrom which can be configured to removably lock the cartridge bodies  6980  in their respective retention channels. In at least one such embodiment, the second jaw  6940  can comprise a distal bump  6915  configured and positioned relative to each retention channel  6949  such that each cartridge body  6980  can flex around the bumps  6915  as the cartridge bodies  6980  are being inserted into the channels  6949  wherein, just as the cartridge bodies  6915  are being fully seated in the channels  6949 , the distal ends of the cartridge bodies  6980  can clear and snap over the bumps  6915 . In order to remove the cartridge bodies  6980  after they have been expended, as described above, the cartridge bodies  6980  can be pulled back over the bumps  6915  and removed from the retention channels  6949 . Similar to the above, the first jaw  6930  can comprise one or more distal retention bumps  6914  extending therefrom which can be configured to be received in one or more retention grooves, or slots,  6912  ( FIG. 158 ) in the cartridge body  6910  when the staple cartridge  6900  has been fully seated. 
     In various embodiments, further to the above, a first fastener cartridge comprising a plurality of first fasteners positioned therein can be positioned in a first jaw of a surgical fastening device and a second fastener cartridge comprising a plurality of second fasteners positioned therein can be positioned in a second jaw of the surgical fastening device. In use, the first jaw and/or the second jaw can be moved toward the other in order to engage the first fasteners with the second fasteners and secure tissue therebetween. In certain embodiments, the first fastener cartridge and the second fastener cartridge can be engaged with each other as the first fasteners are engaged with the second fasteners. In at least one embodiment, the body of the first fastener cartridge can be comprised of a first compressible material and the body of the second fastener cartridge can be comprised of a second compressible material, wherein the first body and/or the second body can be compressed against the tissue being fastened. After the tissue has been fastened, the first jaw can be moved away from the implanted first fastener cartridge and the second jaw can be moved away from the implanted second fastener cartridge. Thereafter, the first jaw can be reloaded with another first fastener cartridge, or the like, and the second jaw can be reloaded with another second fastener cartridge, or the like, and the surgical fastening instrument can be reused. While staples can be used in some embodiments, other embodiments are envisioned comprising other types of fasteners, such as two-part fasteners which are locked together when they are engaged with one another, for example. In at least one such embodiment, the first fastener cartridge can comprise a first storage portion for storing the first fastener portions and the second fastener cartridge can comprise a second storage portion for storing the second fastener portions. In various embodiments, the fastening systems described herein can utilize fasteners comprising any suitable type of material and/or form. In certain embodiments, the fasteners can comprise penetrating members. Such penetrating members could be comprised of a polymer, a composite, and/or a multi-layered substrate, for example. An example of a multi-layered substrate could be a wire or a sheet substrate with an elastomeric or polymeric coating. It could be a thin sheet formed such that penetrating members are oriented perpendicular, or at least substantially perpendicular, to the connecting member. The penetrating members could comprise a rectangular profile, semi-circular profile, and/or any beam profile. In various embodiments, the fasteners described herein can be manufactured utilizing any suitable process, such as a wire extruding process, for example. Another possibility is the use of microfabrication to create hollow penetrating members. These penetrating members could be fabricated from a process which is different than a wire extruded process and could use a combination of materials. 
     As described above, the tips of staple legs protruding through a retention matrix can be covered by one or more caps and/or covers. In certain embodiments, the tips of the staple legs can be deformed after they have been inserted through the retention matrix. In at least one embodiment, a jaw holding the retention matrix can further comprise anvil pockets positioned above and/or aligned with the retention apertures which can be configured to deform the staple legs as they protrude above the retention matrix. In various embodiments, the staple legs of each staple can be curled inwardly toward each other and/or toward the center of the staple, for example. In certain other embodiments, one or more of the staple legs of a staple can be curled outwardly away from the other staple legs and/or away from the center of the staple. In various embodiments, regardless of the direction in which the staple legs are curled, the tips of the staple legs can contact the body of the retention matrix and may not re-enter the tissue that has been fastened by the staples. In at least one embodiment, the deformation of the staple legs after they have passed through the retention matrix can lock the retention matrix in position. 
     In various embodiments, referring now to  FIGS. 161 and 162 , a surgical stapling instrument, such as surgical stapler  7000 , for example, can comprise a first jaw  7030  and a second jaw  7040 , wherein the second jaw  7040  can be moved toward and away from the first jaw  7030  by the movement of actuator  6235 . The operation of actuator  6235  is described above and is not repeated herein for the sake of brevity. In various embodiments, the first jaw  7030  can comprise a distal end  7031  and a proximal end  7032 , wherein the first jaw  7030  can define a channel extending between the distal end  7031  and the proximal end  7032  which is configured to receive a staple cartridge. For the purposes of illustration, the cartridge body of such a staple cartridge is not depicted in  FIG. 161 , although such a staple cartridge can comprise a cartridge body, staples  6220  positioned within the cartridge body, and staple drivers  7012  positioned underneath the staples  6220 . In certain embodiments, although not illustrated in  FIG. 161  for the sake of clarity, the second jaw  7040  can be configured to hold a retention matrix, such as retention matrix  6250 , for example, over the staples  6220  and/or move the retention matrix into engagement with the legs of the staples  6220  as described above. In at least one embodiment, the surgical stapler  7000  can further comprise a sled  7010  positioned in the first jaw  7030  which can be slid from the distal end  7031  of the first jaw  7030  toward the proximal end  7032 , for example, and lift the staple drivers  7012 , and the staple  6220  supported thereon, toward the retention matrix and the second jaw  7040 . In various other embodiments, the sled  7010  can be moved from the proximal end  7032  toward the distal end  7031  in order to deploy the staples  6020 , for example. In at least one embodiment, the sled  7010  can comprise one or more inclined ramps, or cams,  7011  which can be configured to slide underneath the staple drivers  7012  and lift the staple drivers  7012  upwardly. In various embodiments, the surgical stapler  7000  can further comprise a pull, or push, rod operably coupled to the sled  7010  which can be moved proximally and/or distally by an actuator located on a handle and/or shaft of the surgical stapler  7000 , for example. 
     In various embodiments, referring again to  FIG. 161 , the second jaw  7040  of the surgical stapler  7000  can comprise a frame  7041 , a distal end  7048 , and a proximal end  7049  positioned opposite the distal end  7048 . In certain embodiments, the second jaw  7040  can further comprise a guide system comprising one or more guide rails, such as guide rails  7045  and  7046 , for example, extending along the longitudinal axis of the frame  7041  which, as described in greater detail further below, can be configured to guide one or more anvils, or cams, which can engage and deform the staple legs of the staples  6220  after the staple legs  6221  of the staples  6220  have passed through the retention matrix. In at least one such embodiment, the guide rails  7045  and  7046  can comprise a guide wire or cable which extends along a top portion or surface of the frame  7041 , around a distal post  7047 , and back along the top portion or surface of the frame  7041 , for example. In various embodiments, as mentioned above and referring primarily now to  FIGS. 163 and 165 , the second jaw  7040  can further comprise one or more anvils, or cams, such as first anvil  7050  and second anvil  7060 , for example, which can be moved longitudinally along the second jaw  7040  in order to deform the legs of the staples  6220  after they have passed through the retention matrix. In at least one embodiment, the surgical stapler  7000  can further comprise a first anvil driver, or actuator,  7051  connected to and/or operably coupled to the first anvil  7050  which can be configured to pull the first anvil  7050  proximally and/or push the first anvil  7050  distally. Similarly, in at least one embodiment, the surgical stapler  7000  can further comprise a second anvil driver, or actuator, connected to and/or operably coupled to the second anvil  7060  which can be configured to push the second anvil  7060  distally and/or pull the second anvil  7060  proximally. In various embodiments, the first anvil  7050  can comprise guide slots  7052  and the second anvil  7060  can comprise guide slots  7062  which can each be configured to slidably receive guide rail  7045  or guide rail  7046  therein. In at least one such embodiment, the guide rails  7045  and  7046  can be closely received within the guide slots  7052  and  7062  such that relative lateral, or side-to-side, movement therebetween can be prevented, or at least limited. 
     In certain embodiments, further to the above, the first anvil  7050  can be pulled proximally and the second anvil  7060  can be pulled distally. In at least one embodiment, referring to  FIG. 161 , the guide rails  7045  and  7046  and the distal post  7047  can comprise a pulley system configured to pull the second anvil  7060  distally and/or pull the second anvil  7060  proximally. In at least one such embodiment, the guide rail  7045  and the guide rail  7046  can comprise a continuous wire or cable extending around the distal post  7047 , wherein a portion of the continuous wire can be pulled in order to cycle the wire around the distal post  7047 . In various embodiments, the guide rail  7046 , for example, can be mounted to the second anvil  7060  such that, when the continuous cable is cycled in a first direction, the second anvil  7060  can be pulled distally toward the distal end  7048  of the jaw  7040  and, when the continuous cable is cycled in a second, or opposite, direction, the second anvil  7060  can be pulled proximally toward the proximal end  7049 . In at least one embodiment, referring now to  FIG. 163 , the guide rail  7046  can be secured within a guide slot  7062  such that a pulling force can be transmitted therebetween. In at least one such embodiment, the guide rail  7045  can be configured to slide within the other guide slot  7062 . In various embodiments, the first anvil  7050  may operate independently of the second anvil  7060  and the pulley system and the guide slots  7052  defined in the first anvil  7050  may be configured to slidably receive the guide rails  7045  and  7046  such that relative movement is permitted therebetween. In various embodiments, the continuous cable comprising guide rails  7045  and  7046  can be sufficiently flexible in order to accommodate the opening and closing of the top jaw  7040 . The continuous cable can also be sufficiently flexible in order to accommodate the vertical movement of the second anvil  7060  toward and away from the bottom jaw  7030 , which is described in greater detail further below. 
     In various embodiments, referring again to  FIGS. 163 and 165 , the first anvil  7050  can comprise cam followers  7055  extending therefrom which can be configured to ride in one or more cam slots, or guide slots, such as cam slot  7070  ( FIG. 166 ), for example, defined in the frame  7041  of the second jaw  7040 . More particularly, in at least one embodiment, the frame  7041  can comprise a first cam slot  7070  extending longitudinally along a first side of the frame  7041  and a second cam  7070  extending longitudinally along a second, or opposite, side of the frame  7041 , wherein the cam followers  7055  extending from a first side of the first anvil  7050  can ride in the first cam slot  7070  and the cam followers  7055  extending from a second side of the first anvil  7050  can ride in the second cam slot  7070 . In at least one such embodiment, the contours of each cam slot  7070  can be identical, or at least substantially identical, and can be aligned, or at least substantially aligned, with one another. Similarly, in various embodiments, the second anvil  7060  can comprise cam followers  7065  extending therefrom which can be configured to ride in the cam slots  7070  ( FIG. 166 ) defined in the frame  7041  of the second jaw  7040 . More particularly, in at least one embodiment, the cam followers  7065  extending from a first side of the second anvil  7060  can ride in the first cam slot  7070  and the cam followers  7065  extending from a second side of the second anvil  7060  can ride in the second cam slot  7070 . In use, the cam followers  7055  of the first anvil  7050  and the cam followers  7065  of the second anvil  7060  can slide within the cam slots  7070  such that first anvil  7050  and the second anvil  7060  follow the contours of the cam slots  7070  as the first anvil  7050  and the second anvil  7060  are pulled proximally and/or pushed distally. In various embodiments, each cam slot  7070  can comprise a plurality of dwell, or upper, portions  7071  and a plurality of driver, or lower, portions  7072  which can be configured to move the anvils  7050  and  7060  vertically, i.e., toward and away from the bottom jaw  7030 , at the same time that the anvils  7050  and  7060  are being moved longitudinally, i.e., between the distal end  7048  and the proximal end  7049  of the frame  7041 , as described in greater detail further below. 
     When the surgical stapler  7000  is in an unfired condition, referring to  FIG. 166 , the first anvil  7050  can be positioned at the distal end  7048  of the frame  7041  and the second anvil  7060  can be positioned at the proximal end  7049  of the frame  7041 ; furthermore, referring now to  FIG. 167 , the staples  6220  positioned in the first jaw  7030  may not yet be inserted into the tissue T and/or the retention matrix positioned thereabove when the surgical stapler  7000  is in an unfired condition. In use, referring now to  FIG. 168 , the staples  6220  can be driven upwardly within the staple cavities  7033  of a staple cartridge by the staple drivers  7012  and, in addition, the first anvil  7050  can be moved proximally from the distal end  7048  of the frame  7041  toward the distal end  7049  in order to engage the staple legs  6221  of the staples  6220 . In at least one embodiment, the staples  6220  can be driven upwardly before the first anvil  7050  is engaged with the staple legs  6221  thereof. In various embodiments, all of the staples  6220  may be deployed upwardly by the sled  7010  before the first anvil  7050  is advanced into contact with the staple legs  6221  or, alternatively, the sled  7010  may be moved proximally at the same time that the first anvil  7050  is moved proximally, although the sled  7010  may sufficiently lead the first anvil  7050  in order to deploy the staples  6220  ahead of the first anvil  7050 . In various embodiments, as illustrated in  FIG. 168 , the cam slots  7070  can be configured and arranged such that the forming surfaces, such as forming, or camming, surfaces  7053  and  7054 , for example, of the first cam  7050  can contact at least some of the staple legs  6221  when the first cam  7050  is passing through a dwell, or upper, position. In various circumstances, the cam followers  7055  of the first anvil  7050  can each be positioned in a dwell portion  7071  of the cam slots  7070  such that the forming surfaces  7053  and  7054  are in a raised position and such that the staple legs  6221  are only partially deformed when the anvil  7050  passes thereby in the dwell position. As the first cam  7050  is moved further along the cam slots  7070 , as illustrated in  FIG. 169 , the cam followers  7055  of the first anvil  7050  can be driven into driven, or lower, portions  7072  of the cam slots  7070  such that the forming surfaces  7053  and  7054  are moved vertically downwardly toward the staple legs  6021  in order to drive the staple legs  6021  into their finally formed configurations. Thereafter, as the first anvil  7050  is progressed further along the cam slots  7070 , the first anvil  7050  can be driven vertically upwardly into another set of dwell portions  7071  of the cam slots  7070 . As illustrated in  FIGS. 168 and 169 , the reader will note that the first anvil  7050  may only engage some of the staple legs and not others. In at least one such embodiment, the first anvil  7050  can be configured to only deform a group of staple legs comprising the distal staple legs  6221  of the staples  6220 , for example. In at least one such embodiment, the first anvil  7050  can be configured to deform the distal staple legs  6221  toward the center of the staples  6220 . In various embodiments, each proximal staple leg  6221  can be contacted twice by the first anvil  7050 , i.e., by a first forming surface  7053  and by a second forming surface  7054  aligned with the first forming surface  7053 . In at least one such embodiment, the first forming surfaces  7053  can deform the distal staple legs  6221  into a partially-deformed configuration when the first anvil  7050  is in a dwell, or upper, position and the second forming surfaces  7054  can deform the distal staple legs  6221  into a fully-formed configuration when the first anvil  7050  is moved into a driven, or lower, position. In various embodiments, referring now to  FIGS. 163 and 164 , the first anvil  7050  can comprise a plurality of first forming surfaces  7053  and a plurality of second forming surfaces  7054  in order to deform the distal staple legs  6221  of staples  6220  when the staple legs  6221  are arranged in more than one row or line. In various embodiments, as described in greater detail further below, the proximal staple legs  6221  of the staples  6020  can be deformed by the second anvil  7060 , for example. 
     In various embodiments, further to the above, the first anvil  7050  can be moved from the distal end  7048  of the frame  7041  to the proximal end  7049  in order to deform all of the distal staple legs  6221  of the staples  6220 . As the reader will note, the first anvil  7050  can be moved up and down relative to the undeformed proximal staple legs  6221  and, in order to accommodate such relative movement, in various embodiments, the first anvil  7050  can comprise one or more clearance slots  7057  ( FIG. 165 ) which can be configured to receive the unbent proximal staple legs  6221  as the first anvil  7050  bends the distal staple legs  6221 . Similarly, referring again to  FIG. 163 , the second anvil  7060  can comprise a clearance slot  7067  which can be configured to accommodate the vertical movement of the first cam actuator  7051  which moves up and down as the first anvil  7050  is moved between its dwell and driven positions as described above. After all of the distal staple legs  6221  have been bent, in at least one embodiment, the second anvil  7060  can be moved from the proximal end  7049  of the frame  7041  to the distal end  7048  by the anvil actuator  7061 . Similar to the above, referring now to  FIG. 170 , the cam followers  7065  of the second anvil  7060  can slide within the cam slots  7070  such that the second anvil  7060  is moved between dwell, or upper, positions and driven, or lower, positions in order to deform the proximal staple legs  6221  inwardly toward the centers of the staples  6220 , for example. Similar to the above, the second anvil  7060  can comprise a plurality of first forming, or camming, surfaces  7063  and a plurality of second forming, or camming, surfaces  7064  which can each be configured to at least partially deform and/or completely deform one or more of the proximal staple legs  6021 . Referring again to  FIG. 164 , the second anvil  7060  can comprise a plurality of first forming surface  7063  and a plurality of second forming surfaces  7064  which can be configured to deform the proximal staple legs  6221  of staples  6220  arranged in a plurality of rows, or lines, for example. As also illustrated in  FIG. 164 , the first forming surfaces  7063  and the second forming surfaces  7064  of the second anvil  7060  may not be aligned with the first forming surfaces  7053  and the second forming surfaces  7054  of the first anvil  7050  wherein, as a result, the proximal legs  6221  of the staples  6220  may be positioned in different rows, or lines, than the distal legs  6221  of the staples  6220 . As the reader will also note, the second anvil  7060  can push the first anvil  7050  as the second anvil  7060  is moved distally. In at least one such embodiment, the second anvil  7060  can push the first anvil  7050  back into the distal end  7048  of the frame  7041  such that the first anvil  7050  can be returned to its initial, or unfired, position. After all of the proximal staple legs  6221  of the staples  6220  have been deformed, the second anvil  7060  can be retracted proximally and returned to its initial, or unfired, position. In this way, the surgical stapler  7000  can be reset such that a new staple cartridge can be positioned in the first jaw  7030  and a new retention matrix can be positioned in the second jaw  7040  in order to use the surgical stapler  7000  once again. 
     In various embodiments, as described above, a surgical stapler can comprise two or more anvils which can travel longitudinally in order to engage the legs of a plurality of staples in a transverse direction. In certain embodiments, a surgical stapler can comprise an anvil which is moved proximally, for example, in order to deform a first group of staple legs and distally, for example, in order to deform a second group of staple legs. In at least one such embodiment, such an anvil can comprise forming surfaces facing proximally and forming surfaces facing distally, for example. 
     In various embodiments, referring now to  FIG. 171 , an anvil, such as anvil  7140 , for example, can comprise a bottom, or tissue-contacting, surface  7141  and a plurality of forming pockets  7142  defined therein. In at least one embodiment, the anvil  7140  can comprise more than one plate, such as pocket plates  7143 , for example, which can be welded into a frame  7144 . In at least one such embodiment, each pocket plate  7143  can be positioned in a plate channel  7145  in the frame  7144  and welded to the frame  7144  through a weld slot  7146  extending through the frame  7144  in order to form a longitudinal weld  7147 . In various circumstances, the longitudinal weld  7147  can comprise a continuous weld extending along the entire length of the weld slot  7146  or a series of spaced-apart spot welds extending along the length thereof, for example. In various embodiments, each pocket plate  7143  can comprise two or more plate portions that have been welded together. In at least one such embodiment, each pocket plate  7143  can comprise a first plate portion  7143   a  and a second plate portion  7143   b  which can be welded together along a seam  7148 . In various embodiments, the first plate portion  7143   a  and the second plate portion  7143   b  of each plate  7143  can be welded together before the plates  7143  are welded into the plate channels  7145  in the frame  7144 . In at least one such embodiment, the first plate portion  7143   a  and the second plate portion  7143   b  can comprise co-operating profiles, such as the toothed profiles illustrated in  FIG. 171 , for example, which can be fitted together to form a tight seam  7148 . In at least one embodiment, each plate  7143  can comprise a height of approximately 0.02″, for example, which can be taller than the depth of the plate channels  7145  such that the tissue-contacting surfaces  7141  thereof extend from the frame  7044  of the anvil  7040 . In certain embodiments, referring now to  FIG. 172 , the plates  7143  can be connected together by at least one weld  7149  at the distal ends of the plates  7143 , for example. 
     As illustrated in  FIGS. 171 and 172 , each pocket plate  7143  can comprise a plurality of forming pockets  7142  defined therein. In various embodiments, the forming pockets  7142  can be formed in the plates  7143  by any suitable manufacturing process, such as a grinding process and/or electrode-burning process, for example. In at least one such embodiment, referring now to  FIGS. 173 and 174 , each forming pocket  7142  can be manufactured by first forming a deep well  7150 , then forming an arcuate or curved surface  7151  surrounding the deep well  7150 , and then forming a staple leg guide groove  7152  in the curved surface  7151 , for example. In various other embodiments, these steps can be performed in any suitable order. In various embodiments, referring now to  FIG. 175 , the staple forming pockets  7142  can be formed such that the inner edges  7153  of the forming pockets are separated by a consistent, or at least substantially consistent, gap  7154 . In at least one such embodiment, the gap  7154  can be approximately 0.008″, for example. Furthermore, in at least one such embodiment, the forming pockets  7142  can be positioned along two or more rows, or lines, the centerlines of which can be separated by a consistent, or at least substantially consistent, spacing  7155 . In at least one such embodiment, the spacing  7155  between the centerlines can be approximately 0.035″, for example. In various embodiments, referring again to  FIG. 175 , each forming pocket  7142  can taper between a narrow width  7156  and a wide width  7157 . In at least one such embodiment, the narrow width  7156  can be approximately 0.045″ and the wide width  7157  can be approximately 0.075″, for example. In various embodiments, the plates  7143  can be comprised of the same material as the frame  7144 . In at least one such embodiment, the plates  7143  and the frame  7144  can both be comprised of stainless steel, such as a 300 series or a 400 series stainless steel, for example, and/or titanium, for example. In various other embodiments, the plates  7143  and the frame  7144  can be comprised of different materials. In at least one such embodiment, the plates  7143  can be comprised of a ceramic material, for example, and the frame  7144  can be comprised of a stainless steel and/or titanium, for example. In various circumstances, depending on the materials used, at least one brazing process could be used to secure the plates  7143  in the frame  7144  in addition to or in lieu of the welding processes described above, for example. 
     In various embodiments, referring now to  FIGS. 176-178 , an anvil  7240  can comprise a frame  7244  and a plurality of pocket plates  7243  which can be inserted into the frame  7244 . Similar to the above, each pocket plate  7243  can comprise a plurality of forming pockets  7242  defined therein. In at least one embodiment, the anvil frame  7244  can comprise retention slots  7246  defined therein which can each be configured to receive a retention rail  7247  extending from a pocket plate  7243 . In order to assemble the pocket plates  7243  to the anvil frame  7244 , the side walls  7245  of the anvil frame  7244  can be flexed or splayed outwardly, as illustrated in  FIG. 177 , in order to widen the retention slots  7246  such that each retention slot  7246  can receive a retention rail  7247  of a pocket plate  7243  therein. Once the retention rails  7247  have been positioned in the retention slots  7246 , the side walls  7245  can be released, as illustrated in  FIG. 178 , thereby allowing the frame  7244  to resiliently contract and/or return to its unflexed state. In such circumstances, the retention slots  7246  can contract and thereby capture the retention rails  7247  therein. In certain embodiments, the retention rails  7247  and/or the retention slots  7246  can comprise one or more co-operating tapered surfaces which, after the flexed retention slots  7246  have been released, can form a taper-lock engagement which can retain the retention rails  7247  in the retention slots  7246 . Similar to the above, the pocket plates  7243  can be comprised of the same material as or a different material than the frame  7244 . In at least one such embodiment, the plates  7243  can be comprised of a ceramic material, for example, and the frame  7244  can be comprised of a stainless steel and/or titanium, for example. In various circumstances, depending on the materials used, at least one brazing process and/or at least one welding process, for example, could be used to secure the plates  7243  in the frame  7244 . 
     In  FIGS. 179 and 180 , a surgical stapling and severing instrument  8010  can comprise an anvil  8014  which may be repeatably opened and closed about its pivotal attachment to an elongate staple channel  8016 . A staple applying assembly  8012  can comprise the anvil  8014  and the channel  8016 , wherein the assembly  8012  can be proximally attached to the elongate shaft  8018  forming an implement portion  8022 . When the staple applying assembly  8012  is closed, or at least substantially closed, the implement portion  8022  can present a sufficiently small cross-section suitable for inserting the staple applying assembly  8012  through a trocar. In various embodiments, the assembly  8012  can be manipulated by a handle  8020  connected to the shaft  8018 . The handle  8020  can comprise user controls such as a rotation knob  8030  that rotates the elongate shaft  8018  and staple applying assembly  8012  about a longitudinal axis of the shaft  8018 . A closure trigger  8026 , which can pivot in front of a pistol grip  8036  about a closure trigger pin  8152  ( FIG. 181 ) engaged laterally across the handle housing  8154 , can be depressed to close the staple applying assembly  8012 . In various embodiments, a closure release button  8038  can be outwardly presented on the handle  8020  when the closure trigger  8026  is clamped such that the release button  8038  can be depressed to unclamp the closure trigger  8026  and open the staple applying assembly  8012 , as described in greater detail below. A firing trigger  8034 , which can pivot in front of the closure trigger  8026 , can cause the staple applying assembly  8012  to simultaneously sever and staple tissue clamped therein. In various circumstances, as described in greater detail below, multiple firing strokes can be employed using the firing trigger  8034  to reduce the amount of force required to be applied by the surgeon&#39;s hand per stroke. In certain embodiments, the handle  8020  can comprise rotatable right and/or left indicator wheels  8040 ,  8041  ( FIG. 181 ) which can indicate the firing progress. For instance, full firing travel may require three full firing strokes of firing trigger  8034  and thus the indicator wheels  8040 ,  8041  can rotate up to one-third of a revolution each per stroke of firing trigger  8034 . As described in greater detail below, a manual firing release lever  8042  can allow the firing system to be retracted before full firing travel has been completed, if desired, and, in addition, the firing release lever  8042  can allow a surgeon, or other clinician, to retract the firing system in the event that the firing system binds and/or fails. 
     With reference to  FIGS. 179 and 181 , the elongate shaft  8018  can comprise an outer structure including a longitudinally reciprocating closure tube  8024  that pivots the anvil  8014  toward its close position in response to the proximal depression of the closure trigger  8026  of handle  8020 . The elongate channel  8018  can be connected to the handle  8020  by a frame  8028  ( FIG. 181 ) that is internal to the closure tube  8024 . The frame  8028  can be rotatably engaged to the handle  8020  so that the rotation of the rotation knob  8030  ( FIG. 179 ) can rotate the implement portion  8022 . With particular reference to  FIG. 181 , the rotation knob  8030  can be comprised of two half-shells which can include one or more inward projections  8031  that can extend through one or more elongate side openings  8070  in the closure tube  8024  and engage the frame  8028 . As a result of the above, the rotation knob  8030  and the frame  8028  can be rotated together, or synchronously, such that the rotated position of knob  8030  determines the rotated position of the implement portion  8022 . In various embodiments, the longitudinal length of the longer opening  8070  is sufficiently long to allow the longitudinal closure motion, and opening motion, of the closure tube  8024 . With regard to generating the closure motion of closure tube  8024 , referring primarily to  FIGS. 181 and 183 , an upper portion  8160  of the closure trigger  8026  can push forward a closure yoke  8162  via a closure link  8164 . The closure link  8164  is pivotally attached at its distal end by a closure yoke pin  8166  to the closure yoke  8162  and is pivotally attached at its proximal end by a closure link pin  8168 . In various embodiments, the closure trigger  8026  can be urged to an open position by a closure trigger tension spring  8246  that is connected proximally to the upper portion  8160  of the closure trigger  8026  and a handle housing  8154  formed by right and left half shells  8156 ,  8158 . The tension force applied by the tension spring  8246  can be overcome by a closing force applied to the closure trigger  8026  in order to advance the yoke  8162 , closure link  8164 , and the closure tube  8024  distally. 
     As the closure trigger  8026  is actuated, or depressed, as described above, the closure release button  8038  can be positioned such that the surgeon, or other clinician, can push the closure release button  8038 , if desired, and allow the closure trigger  8026 , and the rest of the surgical instrument, to return to an unactuated state. In various embodiments, the closure release button  8038  can be connected to a pivoting locking arm  8172  by a central lateral pivot  8173  such that motion can be transferred between the release button  8038  and the locking arm  8172 . Referring again to  FIG. 181 , a compression spring  8174  can bias the closure release button  8038  proximally, i.e., clockwise about the central lateral pivot  8173  as viewed from the right and the upper portion  8160  of the closure trigger  8026  can include a proximal crest  8170  with an aft notch  8171 . As the closure trigger  8026  is depressed, the pivoting locking arm  8172  can ride upon the proximal crest  8170  and when the closure trigger  8026  reaches its fully depressed position, it should be appreciated that the aft notch  8171  is presented below the pivoting locking arm  8172  which drops into and locks against the aft notch  8171  under the urging of the compression spring  8174 . At such point, manual depression of the closure release button  8038  rotates the pivoting locking arm  8172  upward and out of aft notch  8171  thereby unlocking the closure trigger  8026  and allowing the closure trigger  8026  to be returned to its unclamped position. 
     Once the closure trigger  8026  is proximally clamped, as discussed above, the firing trigger  8034  can be drawn toward the pistol grip  8036  in order to advance a firing rod  8032  distally from the handle  8020 . In various embodiments, the firing trigger  8034  can pivot about a firing trigger pin  8202  that laterally traverses and is engaged with the right and left half shells  8156 ,  8158  of the handle  8020 . The firing trigger  8034 , when actuated, can advance a linked transmission firing mechanism  8150 . The linked transmission firing mechanism  8150  can be urged into a retracted, unfired, position by a spring  8184  that is, one, attached to the pistol grip  8036  of the handle  8020  and, two, attached to one of the links, for example, of the linked transmission firing mechanism  8150  as described in greater detail below. The spring  8184  can comprise a nonmoving end  8186  connected to the housing  8154  and a moving end  8188  connected to a proximal end  8190  of a steel band  8192 . A distally-disposed end  8194  of the steel band  8192  can be attached to an attachment feature  8195  on a front link  8196   a  of a plurality of links  8196   a - 8196   d  that form a linked rack  8200 . Linked rack  8200  can be flexible such that it can readily retract into the pistol grip  8036  and minimize the length of the handle  8020  and yet form a straight rigid rack assembly that may transfer a significant firing force to and/or through the firing rod  8032 . As described in greater detail below, the firing trigger  8034  can be engaged with a first link  8196   a  during a first actuation of the firing trigger  8034 , engaged with a second link  8196   b  during a second actuation of the firing trigger  8034 , engaged with a third link  8196   c  during a third actuation of the firing trigger  8034 , and engaged with a fourth link  8196   d  during a fourth actuation of the firing trigger  8034 , wherein each actuation of the firing trigger  8034  can advance the linked rack  8200  distally an incremental amount. In various embodiments, further to the above, the multiple strokes of firing trigger  1034  can rotate the right and left indicator gauge wheels  1040 ,  1041  to indicate the distance in which the linked rack  8200  has been advanced. 
     Referring now to  FIGS. 181 and 183 , an anti-backup mechanism  8250  can prevent the combination tension/compression spring  8184  from retracting the linked rack  8200  between firing strokes. In various embodiments, a coupling slide tube  8131  abuts the first link  8196   a  and connects to the firing rod  8032  to communicate the firing motion. The firing rod  8032  extends proximally out of a proximal end of the frame  8028  and through a through hole  8408  of an anti-backup plate  8266 . The through hole  8408  is sized to slidingly receive the firing rod  8032  when perpendicularly aligned but to bind when tipped. A lower tab attachment  8271  extends proximally from a lower lip of the proximal end of the frame  8028 , extending through an aperture  8269  on a lower edge of the anti-backup plate  8266 . This lower tab attachment  8271  draws the lower portion of the anti-backup plate  8266  proximate to the frame  8028  so that the anti-backup plate  8266  is perpendicular when the firing rod  8032  is distally advanced and allowed to tip top aft into a binding state when the firing rod  8032  attempts to retract. An anti-backup compression spring  8264  is distally constrained by the proximal end of the frame  8028  and proximally abuts a top portion of the anti-backup plate  8266 , biasing the anti-backup plate  8266  to a locking state. Opposing the spring bias, an anti-backup cam tube  8268  slidingly encompasses the coupling slide tube  8131  and abuts the anti-backup plate  8266 . A proximally projecting anti-backup yoke  8256  attached to the anti-backup cam tube  8268  extends overtop of the closure yoke  8162 . 
     Referring to  FIG. 181 , a link triggered automatic retraction mechanism  8289  is incorporated into the surgical stapling and severing instrument  8010  to cause knife retraction at the end of full firing travel. To that end, the distal link  8196   d  includes a tang  8290  that projects upwardly when the distal link  8196   d  is advanced into rack channel  8291  ( FIG. 181 ) formed in the closure yoke  8162 . This tang  8290  is aligned to activate a bottom proximal cam  8292  on an anti-backup release lever  8248  ( FIG. 186 ). With particular reference to  FIGS. 186 and 187 , structures formed in the right and left half shells  8156 ,  8158  constrain movement of the anti-backup release lever  8248 . A pin receptacle  8296  and circular pin  8293  formed respectively between right and left half shells  8156 ,  8158  is received through a longitudinally elongate aperture  8294  formed in the anti-backup release lever  8248  distal to the bottom proximal cam  8292 , thus allowing longitudinal translation as well as rotation about the circular pin  8293 . In the right half shell  8156 , a proximally open channel  8295  includes a proximal horizontal portion  8295   a  that communicates with an upwardly and distally angled portion  8295   b  that receives a rightward aft pin  8297  ( FIG. 187 ) near the proximal end of the anti-backup release lever  8248 , thus imparting an upward rotation as the anti-backup release lever  8248  reaches the distal most portion of its translation. A blocking structure formed in the right half shell  8156  proximal to the anti-backup release lever  8248  prevents proximal movement thereof once assembled to maintain rightward aft pin  8297  in the proximally open channel  8295 . 
     Further to the above, as depicted in  FIGS. 187 and 188 , a distal end  8254  of the anti-backup release lever  8248  thus is urged distally and downwardly, causing a rightward front pin  8298  to drop into distally open step structure  8299  formed in the right half shell  8156 , which is urged into this engagement by a compression spring  8300  ( FIG. 188 ) hooked to a leftward hook  8301  on the anti-backup release lever  8248  between the rightward front pin  8298  and the longitudinally elongate aperture  8294 . The other end of the compression spring  8300  is attached to a hook  8302  ( FIGS. 186, 188, 189 ) formed in the right half shell  8156  in a more proximal and lower position just above the closure yoke  8266 . The compression spring  8300  thus pulls the distal end  8254  of the anti-backup release lever  8248  down and aft, which results in the rightward front pin  8298  locking into the distally open step structure  8299  when distally advanced. Thus, once tripped, referring to  FIG. 189 , the anti-backup release lever  8248  remains forward holding the anti-backup plate  8266  perpendicularly and thus allowing the linked rack  8200  to be retracted. When the closure yoke  8266  is subsequently retracted when unclamping the end effector  8012 , an upwardly projecting reset tang  8303  on the closure yoke  8266  contacts a bottom distal cam  8305  of the anti-backup release lever  8248 , lifting the rightward front pin  8298  out of the distally open step structure  8299  so that the anti-backup compression spring  8264  can proximally push the anti-backup cam tube  8268  and the anti-backup release lever  8248  to their retracted positions ( FIG. 186 ). 
     In various embodiments, referring to  FIGS. 179 and 189 , the firing trigger  8034  can be operably engaged to the linked rack  8200  in any suitable manner. With particular reference to  FIGS. 180 and 185 , the firing trigger  8034  pivots about a firing trigger pin  8202  that is connected to the housing  8154 . An upper portion  8204  of the firing trigger  8034  moves distally about the firing trigger pin  8202  as the firing trigger  8034  is depressed towards pistol grip  8036 , stretching a proximally placed firing trigger tension spring  8206  ( FIG. 181 ) proximally connected between the upper portion  8204  of the firing trigger  8034  and the housing  8154 . The upper portion  8204  of the firing trigger  8034  engages the linked rack  8200  during each firing trigger depression via a spring biased side pawl mechanism  8210 . When the firing trigger is released, the side pawl mechanism is disengaged from the linked rack  8200  and the firing trigger can be returned to an undepressed, or unfired, position. In use, a ramped right-side track formed by a proximally and rightwardly facing beveled surface  8284  in each of the links  8196   a - 8196   d  is engaged by a side pawl assembly  8285 . In particular, a pawl slide  8270  ( FIGS. 181 and 183 ) has right and left lower guides  8272  that slide respectively in a left track  8274  ( FIG. 181 ) formed in the closure yoke  8266  below the rack channel  8291  and a right track  8275  in a closure yoke rail  8276  that parallels rack channel  8291  and is attached to a rack channel cover  8277  that closes a rightwardly open portion of the rack channel  8291  in the closure yoke  8266  that is distal to the travel of the pawl slide  8270 . In  FIGS. 181, 182, and 185 , a compression spring  8278  is attached between a hook  8279  on a top proximal position on the closure yoke rail  8276  and a hook  8280  on a distal right-side of the pawl slide  8270 , which keeps the pawl slide  8270  drawn proximally into contact with the upper portion  8204  of the firing trigger  8034 . 
     With particular reference to  FIG. 181 , a pawl block  8318  sits on the pawl slide  8270  pivoting about a vertical aft pin  8320  that passes through a left proximal corner of pawl block  8318  and pawl slide  8270 . A kick-out block recess  8322  is formed on a distal portion of a top surface of the block  8318  to receive a kick-out block  8324  pivotally pinned therein by a vertical pin  8326  whose bottom tip extends into a pawl spring recess  8328  on a top surface of the pawl slide  8270 . A pawl spring  8330  in the pawl spring recess  8328  extends to the right of the vertical front pin  8326  urging the pawl block  8318  to rotate counterclockwise when viewed from above into engagement with the ramped right-side track  8282 . A small coil spring  8332  in the kick-out block recess  8322  urges the kick-out block  8324  to rotate clockwise when viewed from above, its proximal end urged into contact with a contoured lip  8334  formed in the closure yoke  8266  above the rack channel  8291 . As shown in  FIG. 184 , the stronger mechanical advantage of the pawl spring  8330  over the small coil spring  8332  means that the pawl block  8318  tends toward engagement with the kick-out block  8324  rotated clockwise. In  FIG. 185 , as the firing trigger  8034  is fully depressed and begins to be release, the kick-out block  8324  encounters a ridge  8336  in the contoured lip  8334  as the pawl slide  8270  retracts, forcing the kick-out block  8324  to rotate clockwise when viewed from above and thereby kicking out the pawl block  8318  from engagement with the linked rack  8200 . The shape of the kick-out block recess  8322  stops the clockwise rotation of the kick-out block  8324  to a perpendicular orientation to the contoured lip  8334  maintaining this disengagement during the full retraction and thereby eliminating a ratcheting noise. 
     In  FIGS. 181, 183, 190, and 195 , the surgical stapling and severing instrument  8010  can include a manual retraction mechanism  8500  that provides for a manual release of the firing mechanism, manual retraction, and in one version ( FIGS. 196-202 ) further performs automatic retraction at the end of full firing travel. Referring now to  FIGS. 181, 190, and 191 , in particular, a front idler gear  8220  is engaged with a toothed upper, left surface  8222  of the linked rack  8200  wherein the front idler gear  8220  also engages an aft idler gear  8230  having a smaller right-side ratchet gear  8231 . Both the front idler gear  8220  and aft idler gear  8230  are rotatably connected to the handle housing  8154  respectively on front idler axle  8232  and aft idler axle  8234 . Each end of the aft axle  8232  extend through the respective right and left housing half shells  8156 ,  8158  and are attached to the left and right indicator gauge wheels  8040 ,  8041  and, since the aft axle  8234  is free spinning in the handle housing  8154  and has a keyed engagement to the aft gear  8230 , the indicator gauge wheels  8040 ,  8041  rotate with the aft gear  8230 . The gear relationship between the linked rack  8200 , idler gear  8220  and aft gear  8230  may be advantageously selected so that the toothed upper surface  8222  has tooth dimensions that are suitably strong and that the aft gear  8230  makes no more than one revolution during the full firing travel of the linked transmission firing mechanism  8150 . In addition to gear mechanism  8502  visually indicating the firing travel, or progress, the gear mechanism  8502  can also be used to manual retract the knife. In various embodiments, the smaller right-side ratchet gear  8231  of the aft idler gear  8230  extends into a hub  8506  of the manual retraction lever  8042 , specifically aligned with a vertical longitudinally-aligned slot  8508  ( FIG. 190 ) bisecting the hub  8506 . A lateral through hole  8510  of the hub  8506  communicates with an upper recess  8512 . A front portion  8514  is shaped to receive a proximally directed locking pawl  8516  that pivots about a rightward lateral pin  8518  formed in a distal end of the upper recess  8512 . An aft portion  8520  is shaped to receive an L-shaped spring tab  8522  that urges the locking pawl  8516  downward into engagement with the right-side smaller ratchet gear  8231 . A hold-up structure  8524  ( FIGS. 186 and 193 ) projects from the right half shell  8156  into the upper recess  8512  holding up the locking pawl  8516  from engaging the smaller right-side ratchet gear  8231  when the manual retraction lever  8042  is down ( FIG. 193 ). A coil spring  8525  ( FIG. 181 ) urges the manual retraction lever  8042  down. 
     In use, as depicted in  FIGS. 192 and 193 , the combination tension/compression spring  8184  may become disconnected with the linked rack distally positioned. In  FIGS. 194 and 195 , as the manual retraction lever  8042  is raised, the locking pawl  8516  rotates clockwise and no longer is held up by the hold-up structure  8524  and engages the smaller right-side ratcheting gear  8231 , rotating the aft idler gear  8230  clockwise when viewed from the left. Thus, the forward idler gear  8220  responds counterclockwise retracting the linked rack  8200 . In addition, a rightward curved ridge  8510  projects out from the hub  8506 , sized to contact and distally move the anti-backup release lever  8248  to release the anti-backup mechanism  8250  as the manual retraction lever  8042  is rotated. 
     In  FIGS. 196-202 , an automatic retraction mechanism  8600  for a surgical stapling and severing instrument  8010   a  can incorporate automatic retraction at the end of full firing travel into a front idler gear  8220   a  having a tooth  8602  that moves within a circular groove  8604  in a cam wheel  8606  until encountering a blockage  8608  after nearly a full rotation corresponding to three firing strokes. In such circumstances, rightward ridge  8610  is rotated upward into contact a bottom cam recess  8612  to distally move an anti-backup release lever  8248   a . With particular reference to  FIG. 197 , the anti-backup release lever  8248   a  includes the distal end  8254  that operates as previously described. The circular pin  8293  and pin receptacle  8296  formed between right and left half shells  8156 ,  8158  is received through a generally rectangular aperture  8294   a  formed in the anti-backup release lever  8248   a  aft of the bottom cam  8192 , thus allowing longitudinal translation as well as downward locking motion of the distal end  8254  of the anti-backup release lever  8248   a . In the right half shell  8156 , a horizontal proximally open channel  8295   a  receives the rightward aft pin  8297  near the proximal end of the anti-backup release lever  8248   a.    
     In operation, before firing in  FIGS. 198, 198A , the linked rack  8200  and the anti-backup cam tube  8268  are in a retracted position, locking the anti-backup mechanism  8250  as the anti-backup compression spring  8264  proximally tips the anti-backup plate  8266 . The automatic retraction mechanism  8600  is at an initial state with the anti-backup release lever  8248   a  retracted with link  8196   a  in contact with the forward idler gear  8220   a . The tooth  8602  is at a six o&#39;clock position with full travel of the circular groove  8604  progressing counterclockwise thereof with the rightward ridge  8610  just proximal to the tooth  8602 . In  FIGS. 199, 199A , one firing stroke has occurred moving up one distal link  8196   b  into contact with the forward idler gear  8220   a . The tooth  8602  has progressed one third of a turn through the circular groove  8604  of the immobile cam wheel  8606 . In  FIGS. 200, 200A , a second firing stroke has occurred moving up one more link  8196   c  into contact with the forward idler gear  8220   a . The tooth  8602  has progressed two thirds of a turn through the circular groove  8604  of the immobile cam wheel  8606 . In  FIGS. 201, 201A , a third firing stroke has occurred moving up one distal link  8196   d  into contact with the forward idler gear  8220   a . The tooth  8602  has progressed fully around the circular groove  8604  into contact with the blockage  8608  initiating counterclockwise rotation (when viewed from the right) of the cam wheel  8606  bringing the rightward ridge  8608  into contact with the anti-backup release lever  8248   a . In  FIG. 202 , the anti-backup release lever  8248   a  has moved distally in response thereto, locking the rightward front pin  8298  into the distally open step structure  8299  and releasing the anti-backup mechanism  8250 . Similar surgical stapling instruments are disclosed in U.S. Pat. No. 7,083,075, which issued on Aug. 1, 2006, the entire disclosure of which is incorporated by reference herein. 
     Referring to  FIG. 203 , the staple applying assembly  9012  of a surgical stapling instrument  9010  accomplishes the functions of clamping onto tissue, driving staples and severing tissue by two distinct motions transferred longitudinally down the shaft  9016  relative to a shaft frame  9070 . This shaft frame  9070  is proximally attached to a handle of a surgical stapling instrument and is coupled thereto for rotation about a longitudinal axis. An illustrative multistroke handle for the surgical stapling and severing instrument is described in greater detail in the co-owned U.S. patent application entitled SURGICAL STAPLING INSTRUMENT INCORPORATING A MULTISTROKE FIRING POSITION INDICATOR AND RETRACTION MECHANISM, Ser. No. 10/674,026, now U.S. Pat. No. 7,364,061, the disclosure of which is hereby incorporated by reference in its entirety. Other applications consistent with the present invention may incorporate a single firing stroke, such as described in commonly owned U.S. patent application SURGICAL STAPLING INSTRUMENT HAVING SEPARATE DISTINCT CLOSING AND FIRING SYSTEMS, Ser. No. 10/441,632, now U.S. Pat. No. 7,000,818, the disclosure of which is hereby incorporated by reference in its entirety. 
     With particular reference to  FIG. 204 , the distal end of the shaft frame  9070  is attached to the staple channel  9018 . The anvil  9022  has a proximal pivoting end  9072  that is pivotally received within a proximal end  9074  of the staple channel  9018 , just distal to its engagement to the shaft frame  9070 . When the anvil  9022  is pivoted downwardly, the anvil  9022  moves a tissue contacting surface  9028  and forming pockets  9026  toward an opposing staple cartridge, described in greater detail further below. The pivoting end  9072  of the anvil  9022  includes a closure feature  9076  proximate but distal to its pivotal attachment with the staple channel  9018 . Thus, a closure tube  9078 , whose distal end includes a horseshoe aperture  9080  that engages this closure feature  9076 , selectively imparts an opening motion to the anvil  9022  during proximal longitudinal motion and a closing motion to the anvil  9022  during distal longitudinal motion of the closure tube  9078  sliding over the shaft frame  9070  in response to a closure trigger, similar to the above. The shaft frame  9070  encompasses and guides a firing motion from the handle through a longitudinally reciprocating, two-piece knife and firing bar  9090 . In particular, the shaft frame  9070  includes a longitudinal firing bar slot  9092  that receives a proximal portion of the two-piece knife and firing bar  9090 , specifically a laminate tapered firing bar  9094 . It should be appreciated that the laminated tapered firing bar  9094  may be substituted with a solid firing bar and/or any other suitable materials. 
     An E-beam  9102  is the distal portion of the two-piece knife and firing bar  9090 , which facilitates separate closure and firing as well as spacing of the anvil  9022  from the elongate staple channel  9018  during firing. With particular reference to  FIGS. 204 and 205 , in addition to any attachment treatment such as brazing or an adhesive, the knife and firing bar  9090  are formed of a female vertical attachment aperture  9104  proximally formed in the E-beam  9102  that receives a corresponding male attachment member  9106  distally presented by the laminated tapered firing bar  9094 , allowing each portion to be formed of a selected material and process suitable for their disparate functions (e.g., strength, flexibility, friction). The E-beam  9102  may be advantageously formed of a material having suitable material properties for forming a pair of top pins  9110 , a pair of middle pins  9112  and a bottom pin or foot  9114 , as well as being able to acquire a sharp cutting edge  9116 . In addition, integrally formed and proximally projecting top guide  9118  and middle guide  9120  bracketing each vertical end of the cutting edge  9116  further define a tissue staging area  9122  assisting in guiding tissue to the sharp cutting edge  9116  prior to being severed. The middle guide  9120  also serves to engage and fire the staple applying apparatus  9012  by abutting a stepped central member  9124  of a wedge sled  9126  ( FIG. 206 ) that effects staple formation by the staple applying assembly  9012 , as described in greater detail below. Forming these features (e.g., top pins  9110 , middle pins  9112 , and bottom foot  9114 ) integrally with the E-beam  9102  facilitates manufacturing at tighter tolerances relative to one another as compared to being assembled from a plurality of parts, ensuring desired operation during firing and/or effective interaction with various lockout features of the staple applying assembly  9012 . 
     In  FIGS. 207 and 208 , the staple applying assembly  9012  is shown open, with the E-beam  9102  fully retracted. During assembly, the lower foot  9114  of the E-beam  9102  is dropped through a widened hole  9130  in the staple channel  9018  and the E-beam  9102  is then advanced such that the E-beam  9102  slides distally along a lower track  9132  formed in the staple channel  9018 . In particular, the lower track  9132  includes a narrow slot  9133  that opens up as a widened slot  9134  on an undersurface of the staple channel  9018  to form an inverted T-shape in lateral cross section, as depicted particularly in  FIGS. 208 and 209 , which communicates with the widened hole  9130 . Once assembled, the components proximally coupled to the laminate tapered firing bar  9094  do not allow the lower foot  9114  to proximally travel again to the widened hole  9130  to permit disengagement. Referring to  FIG. 210 , the laminate tapered firing bar  9094  facilitates insertion of the staple applying assembly  9012  through a trocar. In particular, a more distal, downward projection  9136  raises the E-beam  9102  when fully retracted. This is accomplished by placement of the downward projection  9136  at a point where it cams upwardly on a proximal edge of the widened hole  9130  in the staple channel  9018 . Referring now to  FIG. 211 , the laminate tapered firing bar  9094  also enhances operation of certain lockout features that may be incorporated into the staple channel  9018  by including a more proximal upward projection  9138  that is urged downwardly by the shaft frame  9070  during an initial portion of the firing travel. In particular, a lateral bar  9140  is defined between a pair of square apertures  9142  in the shaft frame  9070  ( FIG. 204 ). A clip spring  9144  that encompasses the lateral bar  9140  downwardly urges a portion of the laminate tapered firing bar  9094  projecting distally out of the longitudinal firing bar slot  9092 , which ensures certain advantageous lockout features are engaged when appropriate. This urging is more pronounced or confined solely to that portion of the firing travel when the upward projection  9138  contacts the clip spring  9144 . 
     In  FIGS. 207 and 208 , the E-beam  9102  is retracted with the top pins  9110  thereof residing within an anvil pocket  9150  near the pivoting proximal end of the anvil  9022 . A downwardly open vertical anvil slot  9152  ( FIG. 203 ) laterally widens in the anvil  9022  into an anvil internal track  9154  that captures the top pins  9110  of the E-beam  9102  as they distally advance during firing, as depicted in  FIGS. 210 and 211 , affirmatively spacing the anvil  9022  from the staple channel  9018 . Thus, with the E-beam  9102  retracted, the surgeon is able to repeatably open and close the staple applying assembly  9012  until satisfied with the placement and orientation of tissue captured therein for stapling and severing, yet the E-beam  9102  assists in proper positioning of tissue even for a staple applying assembly  9012  of reduced diameter and correspondingly reduced rigidity. In  FIGS. 203, 204, 206, 207, 209, and 215 , the staple applying assembly  9012  is shown with the replaceable staple cartridge  9020  that includes the wedge sled  9126 . Longitudinally aligned and parallel plurality of downwardly open wedge slots  9202  ( FIG. 209 ) receive respective wedges  9204  integral to the wedge sled  9126 . In  FIGS. 209-211 , the wedge sled  9126  thus cams upwardly a plurality of staple drivers  9206  that are vertically slidable within staple driver recesses  9208 . In this illustrative version, each staple driver  9206  includes two vertical prongs, each translating upwardly into a respective staple hole  9210 , or cavity  9024 , to upwardly force out and deform a staple  9023  resting thereupon against a staple forming surface  9214  ( FIG. 211 ) of the anvil  9022 . A central firing recess  9216  ( FIG. 204 ) defined within the staple cartridge  9020  proximate to the staple channel  9018  allows the passage of the bottom, horizontal portion  9218  ( FIG. 206 ) of the wedge sled  9126  as well as the middle pins  9112  of the E-beam  9102 . Specifically, a staple cartridge tray  9220  ( FIGS. 204, 209 ) attaches to and underlies a polymer staple cartridge body  9222  that has the staple driver recesses  9208 , staple holes  9210 , and central firing recess  9216  formed therein. As staples  9023  are thus formed to either side, the sharp cutting edge  9116  enters a vertical through slot  9230  passing through the longitudinal axis of the staple cartridge  9020 , excepting only a most distal end thereof. 
     Firing the staple applying assembly  9012  begins as depicted in  FIG. 211  with the two-piece knife and firing bar  9090  proximally drawn until the downward projection  9136  cams the middle guide  9120  on the E-beam  9102  upward and aft, allowing a new staple cartridge  9020  to be inserted into the staple channel  9018  when the anvil  9022  is open as depicted in  FIGS. 203 and 207 . In  FIG. 212 , the two-piece knife and firing bar  9090  has been distally advanced a small distance, allowing the downward projection  9136  to drop into the widened hole  9130  of the lower track  9132  under the urging of the clip spring  9144  against the upward projection  9138  of the laminate tapered firing bar  9094 . The middle guide  9120  prevents further downward rotation by resting upon the stepped central member  9124  of the wedge sled  9126 , thus maintaining the middle pin  9112  of the E-beam within the central firing recess  9216 . In  FIG. 213 , the two-piece knife and firing bar  9090  has been distally fired, advancing the wedge sled  9126  to cause formation of staples  9023  while severing tissue  9242  clamped between the anvil  9022  and staple cartridge  9020  with the sharp cutting edge  9116 . Thereafter, in  FIG. 214 , the two-piece knife and firing bar  9090  is retracted, leaving the wedge sled  9126  distally positioned. In  FIG. 215 , the middle pin  9112  is allowed to translate down into a lockout recess  9240  formed in the staple channel  9018  (also see  FIGS. 208, 211 ). Thus, the operator would receive a tactile indication as the middle pin  9112  encounters the distal edge of the lockout recess  9240  when the wedge sled  9126  (not shown in  FIG. 215 ) is not proximally positioned (i.e., missing staple cartridge  9020  or spent staple cartridge  9020 ). Similar surgical stapling instruments are disclosed in U.S. Pat. No. 7,380,696, which issued on Jun. 3, 2008, the entire disclosure of which is incorporated by reference herein. 
     In various embodiments, as described above, a staple cartridge can comprise a cartridge body including a plurality of staple cavities defined therein. The cartridge body can comprise a deck and a top deck surface wherein each staple cavity can define an opening in the deck surface. As also described above, a staple can be positioned within each staple cavity such that the staples are stored within the cartridge body until they are ejected therefrom. Prior to being ejected from the cartridge body, in various embodiments, the staples can be contained with the cartridge body such that the staples do not protrude above the deck surface. As the staples are positioned below the deck surface, in such embodiments, the possibility of the staples becoming damaged and/or prematurely contacting the targeted tissue can be reduced. In various circumstances, the staples can be moved between an unfired position in which they do not protrude from the cartridge body and a fired position in which they have emerged from the cartridge body and can contact an anvil positioned opposite the staple cartridge. In various embodiments, the anvil, and/or the forming pockets defined within the anvil, can be positioned a predetermined distance above the deck surface such that, as the staples are being deployed from the cartridge body, the staples are deformed to a predetermined formed height. In some circumstances, the thickness of the tissue captured between the anvil and the staple cartridge may vary and, as a result, thicker tissue may be captured within certain staples while thinner tissue may be captured within certain other staples. In either event, the clamping pressure, or force, applied to the tissue by the staples may vary from staple to staple or vary between a staple on one end of a staple row and a staple on the other end of the staple row, for example. In certain circumstances, the gap between the anvil and the staple cartridge deck can be controlled such that the staples apply a certain minimum clamping pressure within each staple. In some such circumstances, however, significant variation of the clamping pressure within different staples may still exist. 
     In various embodiments described herein, a staple cartridge can comprise means for compensating for the thickness of the tissue captured within the staples deployed from the staple cartridge. In various embodiments, referring to  FIG. 216 , a staple cartridge, such as staple cartridge  10000 , for example, can include a rigid first portion, such as support portion  10010 , for example, and a compressible second portion, such as tissue thickness compensator  10020 , for example. In at least one embodiment, referring primarily to  FIG. 218 , the support portion  10010  can comprise a cartridge body, a top deck surface  10011 , and a plurality of staple cavities  10012  wherein, similar to the above, each staple cavity  10012  can define an opening in the deck surface  10011 . A staple  10030 , for example, can be removably positioned in each staple cavity  10012 . In at least one such embodiment, referring primarily to  FIG. 245  and as described in greater detail below, each staple  10030  can comprise a base  10031  and one or more legs  10032  extending from the base  10031 . Prior to the staples  10030  being deployed, as also described in greater detail below, the bases  10031  of the staples  10030  can be supported by staple drivers positioned within the support portion  10010  and, concurrently, the legs  10032  of the staples  10030  can be at least partially contained within the staple cavities  10012 . In various embodiments, the staples  10030  can be deployed between an unfired position and a fired position such that the legs  10032  move through the tissue thickness compensator  10020 , penetrate through a top surface of the tissue thickness compensator  10020 , penetrate the tissue T, and contact an anvil positioned opposite the staple cartridge  10000 . As the legs  10032  are deformed against the anvil, the legs  10032  of each staple  10030  can capture a portion of the tissue thickness compensator  10020  and a portion of the tissue T within each staple  10030  and apply a compressive force to the tissue. Further to the above, the legs  10032  of each staple  10030  can be deformed downwardly toward the base  10031  of the staple to form a staple entrapment area  10039  in which the tissue T and the tissue thickness compensator  10020  can be captured. In various circumstances, the staple entrapment area  10039  can be defined between the inner surfaces of the deformed legs  10032  and the inner surface of the base  10031 . The size of the entrapment area for a staple can depend on several factors such as the length of the legs, the diameter of the legs, the width of the base, and/or the extent in which the legs are deformed, for example. 
     In previous embodiments, a surgeon was often required to select the appropriate staples having the appropriate staple height for the tissue being stapled. For example, a surgeon could select tall staples for use with thick tissue and short staples for use with thin tissue. In some circumstances, however, the tissue being stapled did not have a consistent thickness and, thus, some staples were unable to achieve the desired fired configuration. For example,  FIG. 250  illustrates a tall staple used in thin tissue. Referring now to  FIG. 251 , when a tissue thickness compensator, such as tissue thickness compensator  10020 , for example, is used with thin tissue, for example, the larger staple may be formed to a desired fired configuration. 
     Owing to the compressibility of the tissue thickness compensator, the tissue thickness compensator can compensate for the thickness of the tissue captured within each staple. More particularly, referring now to  FIGS. 245 and 246 , a tissue thickness compensator, such as tissue thickness compensator  10020 , for example, can consume larger and/or smaller portions of the staple entrapment area  10039  of each staple  10030  depending on the thickness and/or type of tissue contained within the staple entrapment area  10039 . For example, if thinner tissue T is captured within a staple  10030 , the tissue thickness compensator  10020  can consume a larger portion of the staple entrapment area  10039  as compared to circumstances where thicker tissue T is captured within the staple  10030 . Correspondingly, if thicker tissue T is captured within a staple  10030 , the tissue thickness compensator  10020  can consume a smaller portion of the staple entrapment area  10039  as compared to the circumstances where thinner tissue T is captured within the staple  10030 . In this way, the tissue thickness compensator can compensate for thinner tissue and/or thicker tissue and assure that a compressive pressure is applied to the tissue irrespective, or at least substantially irrespective, of the tissue thickness captured within the staples. In addition to the above, the tissue thickness compensator  10020  can compensate for different types, or compressibilities, of tissues captured within different staples  10030 . Referring now to  FIG. 246 , the tissue thickness compensator  10020  can apply a compressive force to vascular tissue T which can include vessels V and, as a result, restrict the flow of blood through the less compressible vessels V while still applying a desired compressive pressure to the surrounding tissue T. In various circumstances, further to the above, the tissue thickness compensator  10020  can also compensate for malformed staples. Referring to  FIG. 247 , the malformation of various staples  10030  can result in larger staple entrapment areas  10039  being defined within such staples. Owing to the resiliency of the tissue thickness compensator  10020 , referring now to  FIG. 248 , the tissue thickness compensator  10020  positioned within malformed staples  10030  may still apply a sufficient compressive pressure to the tissue T eventhough the staple entrapment areas  10039  defined within such malformed staples  10030  may be enlarged. In various circumstances, the tissue thickness compensator  10020  located intermediate adjacent staples  10030  can be biased against the tissue T by properly-formed staples  10030  surrounding a malformed staple  10030  and, as a result, apply a compressive pressure to the tissue surrounding and/or captured within the malformed staple  10030 , for example. In various circumstances, a tissue thickness compensator can compensate for different tissue densities which can arise due to calcifications, fibrous areas, and/or tissue that has been previously stapled or treated, for example. 
     In various embodiments, a fixed, or unchangeable, tissue gap can be defined between the support portion and the anvil and, as a result, the staples may be deformed to a predetermined height regardless of the thickness of the tissue captured within the staples. When a tissue thickness compensator is used with these embodiments, the tissue thickness compensator can adapt to the tissue captured between the anvil and the support portion staple cartridge and, owing to the resiliency of the tissue thickness compensator, the tissue thickness compensator can apply an additional compressive pressure to the tissue. Referring now to  FIGS. 252-257 , a staple  10030  has been formed to a predefined height H. With regard to  FIG. 252 , a tissue thickness compensator has not been utilized and the tissue T consumes the entirety of the staple entrapment area  10039 . With regard to  FIG. 259 , a portion of a tissue thickness compensator  10020  has been captured within the staple  10030 , compressed the tissue T, and consumed at least a portion of the staple entrapment area  10039 . Referring now to  FIG. 254 , thin tissue T has been captured within the staple  10030 . In this embodiment, the compressed tissue T has a height of approximately 2/9H and the compressed tissue thickness compensator  10020  has a height of approximately 7/9H, for example. Referring now to  FIG. 255 , tissue T having an intermediate thickness has been captured within the staple  10030 . In this embodiment, the compressed tissue T has a height of approximately 4/9H and the compressed tissue thickness compensator  10020  has a height of approximately 5/9H, for example. Referring now to  FIG. 256 , tissue T having an intermediate thickness has been captured within the staple  10030 . In this embodiment, the compressed tissue T has a height of approximately 2/3H and the compressed tissue thickness compensator  10020  has a height of approximately 1/3H, for example. Referring now to  FIG. 255 , thick tissue T has been captured within the staple  10030 . In this embodiment, the compressed tissue T has a height of approximately 8/9H and the compressed tissue thickness compensator  10020  has a height of approximately 1/9H, for example. In various circumstances, the tissue thickness compensator can comprise a compressed height which comprises approximately 10% of the staple entrapment height, approximately 20% of the staple entrapment height, approximately 30% of the staple entrapment height, approximately 40% of the staple entrapment height, approximately 50% of the staple entrapment height, approximately 60% of the staple entrapment height, approximately 70% of the staple entrapment height, approximately 80% of the staple entrapment height, and/or approximately 90% of the staple entrapment height, for example. 
     In various embodiments, the staples  10030  can comprise any suitable unformed height. In certain embodiments, the staples  10030  can comprise an unformed height between approximately 2 mm and approximately 4.8 mm, for example. The staples  10030  can comprise an unformed height of approximately 2.0 mm, approximately 2.5 mm, approximately 3.0 mm, approximately 3.4 mm, approximately 3.5 mm, approximately 3.8 mm, approximately 4.0 mm, approximately 4.1 mm, and/or approximately 4.8 mm, for example. In various embodiments, the height H to which the staples can be deformed can be dictated by the distance between the deck surface  10011  of the support portion  10010  and the opposing anvil. In at least one embodiment, the distance between the deck surface  10011  and the tissue-contacting surface of the anvil can be approximately 0.097″, for example. The height H can also be dictated by the depth of the forming pockets defined within the anvil. In at least one embodiment, the forming pockets can have a depth measured from the tissue-contacting surface, for example. In various embodiments, as described in greater detail below, the staple cartridge  10000  can further comprise staple drivers which can lift the staples  10030  toward the anvil and, in at least one embodiment, lift, or “overdrive”, the staples above the deck surface  10011 . In such embodiments, the height H to which the staples  10030  are formed can also be dictated by the distance in which the staples  10030  are overdriven. In at least one such embodiment, the staples  10030  can be overdriven by approximately 0.028″, for example, and can result in the staples  10030  being formed to a height of approximately 0.189″, for example. In various embodiments, the staples  10030  can be formed to a height of approximately 0.8 mm, approximately 1.0 mm, approximately 1.5 mm, approximately 1.8 mm, approximately 2.0 mm, and/or approximately 2.25 mm, for example. In certain embodiments, the staples can be formed to a height between approximately 2.25 mm and approximately 3.0 mm, for example. Further to the above, the height of the staple entrapment area of a staple can be determined by the formed height of the staple and the width, or diameter, of the wire comprising the staple. In various embodiments, the height of the staple entrapment area  10039  of a staple  10030  can comprise the formed height H of the staple less two diameter widths of the wire. In certain embodiments, the staple wire can comprise a diameter of approximately 0.0089″, for example. In various embodiments, the staple wire can comprise a diameter between approximately 0.0069″ and approximately 0.0119″, for example. In at least one exemplary embodiment, the formed height H of a staple  10030  can be approximately 0.189″ and the staple wire diameter can be approximately 0.0089″ resulting in a staple entrapment height of approximately 0.171″, for example. 
     In various embodiments, further to the above, the tissue thickness compensator can comprise an uncompressed, or pre-deployed, height and can be configured to deform to one of a plurality of compressed heights. In certain embodiments, the tissue thickness compensator can comprise an uncompressed height of approximately 0.125″, for example. In various embodiments, the tissue thickness compensator can comprise an uncompressed height of greater than or equal to approximately 0.080″, for example. In at least one embodiment, the tissue thickness compensator can comprise an uncompressed, or pre-deployed, height which is greater than the unfired height of the staples. In at least one embodiment, the uncompressed, or pre-deployed, height of the tissue thickness compensator can be approximately 10% taller, approximately 20% taller, approximately 30% taller, approximately 40% taller, approximately 50% taller, approximately 60% taller, approximately 70% taller, approximately 80% taller, approximately 90% taller, and/or approximately 100% taller than the unfired height of the staples, for example. In at least one embodiment, the uncompressed, or pre-deployed, height of the tissue thickness compensator can be up to approximately 100% taller than the unfired height of the staples, for example. In certain embodiments, the uncompressed, or pre-deployed, height of the tissue thickness compensator can be over 100% taller than the unfired height of the staples, for example. In at least one embodiment, the tissue thickness compensator can comprise an uncompressed height which is equal to the unfired height of the staples. In at least one embodiment, the tissue thickness compensator can comprise an uncompressed height which is less than the unfired height of the staples. In at least one embodiment, the uncompressed, or pre-deployed, height of the thickness compensator can be approximately 10% shorter, approximately 20% shorter, approximately 30% shorter, approximately 40% shorter, approximately 50% shorter, approximately 60% shorter, approximately 70% shorter, approximately 80% shorter, and/or approximately 90% shorter than the unfired height of the staples, for example. In various embodiments, the compressible second portion can comprise an uncompressed height which is taller than an uncompressed height of the tissue T being stapled. In certain embodiments, the tissue thickness compensator can comprise an uncompressed height which is equal to an uncompressed height of the tissue T being stapled. In various embodiments, the tissue thickness compensator can comprise an uncompressed height which is shorter than an uncompressed height of the tissue T being stapled. 
     As described above, a tissue thickness compensator can be compressed within a plurality of formed staples regardless of whether thick tissue or thin tissue is captured within the staples. In at least one exemplary embodiment, the staples within a staple line, or row, can be deformed such that the staple entrapment area of each staple comprises a height of approximately 2.0 mm, for example, wherein the tissue T and the tissue thickness compensator can be compressed within this height. In certain circumstances, the tissue T can comprise a compressed height of approximately 1.75 mm within the staple entrapment area while the tissue thickness compensator can comprise a compressed height of approximately 0.25 mm within the staple entrapment area, thereby totaling the approximately 2.0 mm staple entrapment area height, for example. In certain circumstances, the tissue T can comprise a compressed height of approximately 1.50 mm within the staple entrapment area while the tissue thickness compensator can comprise a compressed height of approximately 0.50 mm within the staple entrapment area, thereby totaling the approximately 2.0 mm staple entrapment area height, for example. In certain circumstances, the tissue T can comprise a compressed height of approximately 1.25 mm within the staple entrapment area while the tissue thickness compensator can comprise a compressed height of approximately 0.75 mm within the staple entrapment area, thereby totaling the approximately 2.0 mm staple entrapment area height, for example. In certain circumstances, the tissue T can comprise a compressed height of approximately 1.0 mm within the staple entrapment area while the tissue thickness compensator can comprise a compressed height of approximately 1.0 mm within the staple entrapment area, thereby totaling the approximately 2.0 mm staple entrapment area height, for example. In certain circumstances, the tissue T can comprise a compressed height of approximately 0.75 mm within the staple entrapment area while the tissue thickness compensator can comprise a compressed height of approximately 1.25 mm within the staple entrapment area, thereby totaling the approximately 2.0 mm staple entrapment area height, for example. In certain circumstances, the tissue T can comprise a compressed height of approximately 1.50 mm within the staple entrapment area while the tissue thickness compensator can comprise a compressed height of approximately 0.50 mm within the staple entrapment area, thereby totaling the approximately 2.0 mm staple entrapment area height, for example. In certain circumstances, the tissue T can comprise a compressed height of approximately 0.25 mm within the staple entrapment area while the tissue thickness compensator can comprise a compressed height of approximately 1.75 mm within the staple entrapment area, thereby totaling the approximately 2.0 mm staple entrapment area height, for example. 
     In various embodiments, further to the above, the tissue thickness compensator can comprise an uncompressed height which is less than the fired height of the staples. In certain embodiments, the tissue thickness compensator can comprise an uncompressed height which is equal to the fired height of the staples. In certain other embodiments, the tissue thickness compensator can comprise an uncompressed height which is taller than the fired height of the staples. In at least one such embodiment, the uncompressed height of a tissue thickness compensator can comprise a thickness which is approximately 110% of the formed staple height, approximately 120% of the formed staple height, approximately 130% of the formed staple height, approximately 140% of the formed staple height, approximately 150% of the formed staple height, approximately 160% of the formed staple height, approximately 170% of the formed staple height, approximately 180% of the formed staple height, approximately 190% of the formed staple height, and/or approximately 200% of the formed staple height, for example. In certain embodiments, the tissue thickness compensator can comprise an uncompressed height which is more than twice the fired height of the staples. In various embodiments, the tissue thickness compensator can comprise a compressed height which is from approximately 85% to approximately 150% of the formed staple height, for example. In various embodiments, as described above, the tissue thickness compensator can be compressed between an uncompressed thickness and a compressed thickness. In certain embodiments, the compressed thickness of a tissue thickness compensator can be approximately 10% of its uncompressed thickness, approximately 20% of its uncompressed thickness, approximately 30% of its uncompressed thickness, approximately 40% of its uncompressed thickness, approximately 50% of its uncompressed thickness, approximately 60% of its uncompressed thickness, approximately 70% of its uncompressed thickness, approximately 80% of its uncompressed thickness, and/or approximately 90% of its uncompressed thickness, for example. In various embodiments, the uncompressed thickness of the tissue thickness compensator can be approximately two times, approximately ten times, approximately fifty times, and/or approximately one hundred times thicker than its compressed thickness, for example. In at least one embodiment, the compressed thickness of the tissue thickness compensator can be between approximately 60% and approximately 99% of its uncompressed thickness. In at least one embodiment, the uncompressed thickness of the tissue thickness compensator can be at least 50% thicker than its compressed thickness. In at least one embodiment, the uncompressed thickness of the tissue thickness compensator can be up to one hundred times thicker than its compressed thickness. In various embodiments, the compressible second portion can be elastic, or at least partially elastic, and can bias the tissue T against the deformed legs of the staples. In at least one such embodiment, the compressible second portion can resiliently expand between the tissue T and the base of the staple in order to push the tissue T against the legs of the staple. In certain embodiments, discussed in further detail below, the tissue thickness compensator can be positioned intermediate the tissue T and the deformed staple legs. In various circumstances, as a result of the above, the tissue thickness compensator can be configured to consume any gaps within the staple entrapment area. 
     In various embodiments, the tissue thickness compensator may comprise a polymeric composition. The polymeric composition may comprise one or more synthetic polymer and/or one or more non-synthetic polymer. The synthetic polymer may comprise a synthetic absorbable polymer and/or a synthetic non-absorbable polymer. In various embodiments, the polymeric composition may comprise a biocompatible foam, for example. The biocompatible foam may comprise a porous, open cell foam and/or a porous, closed cell foam, for example. The biocompatible foam can have a uniform pore morphology or may have a gradient pore morphology (i.e. small pores gradually increasing in size to large pores across the thickness of the foam in one direction). In various embodiments, the polymeric composition may comprise one or more of a porous scaffold, a porous matrix, a gel matrix, a hydrogel matrix, a solution matrix, a filamentous matrix, a tubular matrix, a composite matrix, a membranous matrix, a biostable polymer, and a biodegradable polymer, and combinations thereof. For example, the tissue thickness compensator may comprise a foam reinforced by a filamentous matrix or may comprise a foam having an additional hydrogel layer that expands in the presence of bodily fluids to further provide the compression on the tissue. In various embodiments, a tissue thickness compensator could also be comprised of a coating on a material and/or a second or third layer that expands in the presence of bodily fluids to further provide the compression on the tissue. Such a layer could be a hydrogel that could be a synthetic and/or naturally derived material and could be either biodurable and/or biodegradable, for example. In certain embodiments, a tissue thickness compensator could be reinforced with fibrous non-woven materials or fibrous mesh type elements, for example, that can provide additional flexibility, stiffness, and/or strength. In various embodiments, a tissue thickness compensator that has a porous morphology which exhibits a gradient structure such as, for example, small pores on one surface and larger pores on the other surface. Such morphology could be more optimal for tissue in-growth or haemostatic behavior. Further, the gradient could be also compositional with a varying bio-absorption profile. A short term absorption profile may be preferred to address hemostasis while a long term absorption profile may address better tissue healing without leakages. 
     Examples of non-synthetic polymers include, but are not limited to, lyophilized polysaccharide, glycoprotein, elastin, proteoglycan, gelatin, collagen, and oxidized regenerated cellulose (ORC). Examples of synthetic absorbable polymers include, but are not limited to, poly(lactic acid) (PLA), poly(L-lactic acid) (PLLA), polycaprolactone (PCL), polyglycolic acid (PGA), poly(trimethylene carbonate) (TMC), polyethylene terephthalate (PET), polyhydroxyalkanoate (PHA), a copolymer of glycolide and ε-caprolactone (PGCL), a copolymer of glycolide and -trimethylene carbonate, poly(glycerol sebacate) (PGS), polydioxanone, poly(orthoesters), polyanhydrides, polysaccharides, poly(ester-amides), tyrosine-based polyarylates, tyrosine-based polyiminocarbonates, tyrosine-based polycarbonates, poly(D,L-lactide-urethane), poly(B-hydroxybutyrate), poly(E-caprolactone), polyethyleneglycol (PEG), poly[bis(carboxylatophenoxy) phosphazene], poly(amino acids), pseudo-poly(amino acids), absorbable polyurethanes, and combinations thereof. In various embodiments, the polymeric composition may comprise from approximately 50% to approximately 90% by weight of the polymeric composition of PLLA and approximately 50% to approximately 10% by weight of the polymeric composition of PCL, for example. In at least one embodiment, the polymeric composition may comprise approximately 70% by weight of PLLA and approximately 30% by weight of PCL, for example. In various embodiments, the polymeric composition may comprise from approximately 55% to approximately 85% by weight of the polymeric composition of PGA and 15% to 45% by weight of the polymeric composition of PCL, for example. In at least one embodiment, the polymeric composition may comprise approximately 65% by weight of PGA and approximately 35% by weight of PCL, for example. In various embodiments, the polymeric composition may comprise from approximately 90% to approximately 95% by weight of the polymeric composition of PGA and approximately 5% to approximately 10% by weight of the polymeric composition of PLA, for example. 
     In various embodiments, the synthetic absorbable polymer may comprise a bioabsorbable, biocompatible elastomeric copolymer. Suitable bioabsorbable, biocompatible elastomeric copolymers include but are not limited to copolymers of epsilon-caprolactone and glycolide (preferably having a mole ratio of epsilon-caprolactone to glycolide of from about 30:70 to about 70:30, preferably 35:65 to about 65:35, and more preferably 45:55 to 35:65); elastomeric copolymers of epsilon-caprolactone and lactide, including L-lactide, D-lactide blends thereof or lactic acid copolymers (preferably having a mole ratio of epsilon-caprolactone to lactide of from about 35:65 to about 65:35 and more preferably 45:55 to 30:70) elastomeric copolymers of p-dioxanone (1,4-dioxan-2-one) and lactide including L-lactide, D-lactide and lactic acid (preferably having a mole ratio of p-dioxanone to lactide of from about 40:60 to about 60:40); elastomeric copolymers of epsilon-caprolactone and p-dioxanone (preferably having a mole ratio of epsilon-caprolactone to p-dioxanone of from about 30:70 to about 70:30); elastomeric copolymers of p-dioxanone and trimethylene carbonate (preferably having a mole ratio of p-dioxanone to trimethylene carbonate of from about 30:70 to about 70:30); elastomeric copolymers of trimethylene carbonate and glycolide (preferably having a mole ratio of trimethylene carbonate to glycolide of from about 30:70 to about 70:30); elastomeric copolymer of trimethylene carbonate and lactide including L-lactide, D-lactide, blends thereof or lactic acid copolymers (preferably having a mole ratio of trimethylene carbonate to lactide of from about 30:70 to about 70:30) and blends thereof. In one embodiment, the elastomeric copolymer is a copolymer of glycolide and epsilon-caprolactone. In another embodiment, the elastomeric copolymer is a copolymer of lactide and epsilon-caprolactone. 
     The disclosures of U.S. Pat. No. 5,468,253, entitled ELASTOMERIC MEDICAL DEVICE, which issued on Nov. 21, 1995, and U.S. Pat. No. 6,325,810, entitled FOAM BUTTRESS FOR STAPLING APPARATUS, which issued on Dec. 4, 2001, are hereby incorporated by reference in their respective entireties. 
     In various embodiments, the synthetic absorbable polymer may comprise one or more of 90/10 poly(glycolide-L-lactide) copolymer, commercially available from Ethicon, Inc. under the trade designation VICRYL (polyglactic 910), polyglycolide, commercially available from American Cyanamid Co. under the trade designation DEXON, polydioxanone, commercially available from Ethicon, Inc. under the trade designation PDS, poly(glycolide-trimethylene carbonate) random block copolymer, commercially available from American Cyanamid Co. under the trade designation MAXON, 75/25 poly(glycolide-E-caprolactone-poliglecaprolactone 25) copolymer, commercially available from Ethicon under the trade designation MONOCRYL, for example. 
     Examples of synthetic non-absorbable polymers include, but are not limited to, foamed polyurethane, polypropylene (PP), polyethylene (PE), polycarbonate, polyamides, such as nylon, polyvinylchloride (PVC), polymethylmetacrylate (PMMA), polystyrene (PS), polyester, polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), polytrifluorochloroethylene (PTFCE), polyvinylfluoride (PVF), fluorinated ethylene propylene (FEP), polyacetal, polysulfone, and combinations thereof. The synthetic non-absorbable polymers may include, but are not limited to, foamed elastomers and porous elastomers, such as, for example, silicone, polyisoprene, and rubber. In various embodiments, the synthetic polymers may comprise expanded polytetrafluoroethylene (ePTFE), commercially available from W. L. Gore &amp; Associates, Inc. under the trade designation GORE-TEX Soft Tissue Patch and co-polyetherester urethane foam commercially available from Polyganics under the trade designation NASOPORE. 
     The polymeric composition of a tissue thickness compensator may be characterized by percent porosity, pore size, and/or hardness, for example. In various embodiments, the polymeric composition may have a percent porosity from approximately 30% by volume to approximately 99% by volume, for example. In certain embodiments, the polymeric composition may have a percent porosity from approximately 60% by volume to approximately 98% by volume, for example. In various embodiments, the polymeric composition may have a percent porosity from approximately 85% by volume to approximately 97% by volume, for example. In at least one embodiment, the polymeric composition may comprise approximately 70% by weight of PLLA and approximately 30% by weight of PCL, for example, and can comprise approximately 90% porosity by volume, for example. In at least one such embodiment, as a result, the polymeric composition would comprise approximately 10% copolymer by volume. In at least one embodiment, the polymeric composition may comprise approximately 65% by weight of PGA and approximately 35% by weight of PCL, for example, and can have a percent porosity from approximately 93% by volume to approximately 95% by volume, for example. In various embodiments, the polymeric composition may comprise a greater than 85% porosity by volume. The polymeric composition may have a pore size from approximately 5 micrometers to approximately 2000 micrometers, for example. In various embodiments, the polymeric composition may have a pore size between approximately 10 micrometers to approximately 100 micrometers, for example. In at least one such embodiment, the polymeric composition can comprise a copolymer of PGA and PCL, for example. In certain embodiments, the polymeric composition may have a pore size between approximately 100 micrometers to approximately 1000 micrometers, for example. In at least one such embodiment, the polymeric composition can comprise a copolymer of PLLA and PCL, for example. According to certain aspects, the hardness of a polymeric composition may be expressed in terms of the Shore Hardness, which can defined as the resistance to permanent indentation of a material as determined with a durometer, such as a Shore Durometer. In order to assess the durometer value for a given material, a pressure is applied to the material with a durometer indenter foot in accordance with ASTM procedure D2240-00, entitled, “Standard Test Method for Rubber Property-Durometer Hardness”, the entirety of which is incorporated herein by reference. The durometer indenter foot may be applied to the material for a sufficient period of time, such as 15 seconds, for example, wherein a reading is then taken from the appropriate scale. Depending on the type of scale being used, a reading of 0 can be obtained when the indenter foot completely penetrates the material, and a reading of 100 can be obtained when no penetration into the material occurs. This reading is dimensionless. In various embodiments, the durometer may be determined in accordance with any suitable scale, such as Type A and/or Type OO scales, for example, in accordance with ASTM D2240-00. In various embodiments, the polymeric composition of a tissue thickness compensator may have a Shore A hardness value from approximately 4 A to approximately 16 A, for example, which is approximately 45 OO to approximately 65 OO on the Shore OO range. In at least one such embodiment, the polymeric composition can comprise a PLLA/PCL copolymer or a PGA/PCL copolymer, for example. In various embodiments, the polymeric composition of a tissue thickness compensator may have a Shore A Hardness value of less than 15 A. In various embodiments, the polymeric composition of a tissue thickness compensator may have a Shore A Hardness value of less than 10 A. In various embodiments, the polymeric composition of a tissue thickness compensator may have a Shore A Hardness value of less than 5 A. In certain embodiments, the polymeric material may have a Shore OO composition value from approximately 35 OO to approximately 75 OO, for example. 
     In various embodiments, the polymeric composition may have at least two of the above-identified properties. In various embodiments, the polymeric composition may have at least three of the above-identified properties. The polymeric composition may have a porosity from 85% to 97% by volume, a pore size from 5 micrometers to 2000 micrometers, and a Shore A hardness value from 4 A to 16 A and Shore OO hardness value from 45 OO to 65 OO, for example. In at least one embodiment, the polymeric composition may comprise 70% by weight of the polymeric composition of PLLA and 30% by weight of the polymeric composition of PCL having a porosity of 90% by volume, a pore size from 100 micrometers to 1000 micrometers, and a Shore A hardness value from 4 A to 16 A and Shore OO hardness value from 45 OO to 65 OO, for example. In at least one embodiment, the polymeric composition may comprise 65% by weight of the polymeric composition of PGA and 35% by weight of the polymeric composition of PCL having a porosity from 93% to 95% by volume, a pore size from 10 micrometers to 100 micrometers, and a Shore A hardness value from 4 A to 16 A and Shore OO hardness value from 45 OO to 65 OO, for example. 
     In various embodiments, the polymeric composition may comprise a pharmaceutically active agent. The polymeric composition may release a therapeutically effective amount of the pharmaceutically active agent. In various embodiments, the pharmaceutically active agent may be released as the polymeric composition is desorbed/absorbed. In various embodiments, the pharmaceutically active agent may be released into fluid, such as, for example, blood, passing over or through the polymeric composition. Examples of pharmaceutically active agents may include, but are not limited to, haemostatic agents and drugs, such as, for example, fibrin, thrombin, and oxidized regenerated cellulose (ORC); anti-inflammatory drugs, such as, for example, diclofenac, aspirin, naproxen, sulindac, and hydrocortisone; antibiotic and antimicrobial drug or agents, such as, for example, triclosan, ionic silver, ampicillin, gentamicin, polymyxin B, chloramphenicol; and anticancer agents, such as, for example, cisplatin, mitomycin, adriamycin. 
     In various embodiments, referring now to  FIG. 216 , a staple cartridge, such as staple cartridge  10000 , for example, can comprise a support portion  10010  and a compressible tissue thickness compensator  10020 . Referring now to  FIGS. 218-220 , the support portion  10010  can comprise a deck surface  10011  and a plurality of staple cavities  10012  defined within the support portion  10010 . Each staple cavity  10012  can be sized and configured to removably store a staple, such as a staple  10030 , for example, therein. The staple cartridge  10000  can further comprise a plurality of staple drivers  10040  which can each be configured to support one or more staples  10030  within the staple cavities  10012  when the staples  10030  and the staple drivers  10040  are in their unfired positions. In at least one such embodiment, referring primarily to  FIGS. 224 and 225 , each staple driver  10040  can comprise one or more cradles, or troughs,  10041 , for example, which can be configured to support the staples and limit relative movement between the staples  10030  and the staple drivers  10040 . In various embodiments, referring again to  FIG. 218 , the staple cartridge  10000  can further comprise a staple-firing sled  10050  which can be moved from a proximal end  10001  to a distal end  10002  of the staple cartridge in order to sequentially lift the staple drivers  10040  and the staples  10030  from their unfired positions toward an anvil positioned opposite the staple cartridge  10000 . In certain embodiments, referring primarily to  FIGS. 218 and 220 , each staple  10030  can comprise a base  10031  and one or more legs  10032  extending from the base  10031  wherein each staple can be at least one of substantially U-shaped and substantially V-shaped, for example. In at least one embodiment, the staples  10030  can be configured such that the tips of the staple legs  10032  are recessed with respect to the deck surface  10011  of the support portion  10010  when the staples  10030  are in their unfired positions. In at least one embodiment, the staples  10030  can be configured such that the tips of the staple legs  10032  are flush with respect to the deck surface  10011  of the support portion  10010  when the staples  10030  are in their unfired positions. In at least one embodiment, the staples  10030  can be configured such that the tips of the staple legs  10032 , or at least some portion of the staple legs  10032 , extend above the deck surface  10011  of the support portion  10010  when the staples  10030  are in their unfired positions. In such embodiments, the staple legs  10032  can extend into and can be embedded within the tissue thickness compensator  10020  when the staples  10030  are in their unfired positions. In at least one such embodiment, the staple legs  10032  can extend above the deck surface  10011  by approximately 0.075″, for example. In various embodiments, the staple legs  10032  can extend above the deck surface  10011  by a distance between approximately 0.025″ and approximately 0.125″, for example. In certain embodiments, further to the above, the tissue thickness compensator  10020  can comprise an uncompressed thickness between approximately 0.08″ and approximately 0.125″, for example. 
     In use, further to the above and referring primarily to  FIG. 233 , an anvil, such as anvil,  10060 , for example, can be moved into a closed position opposite the staple cartridge  10000 . As described in greater detail below, the anvil  10060  can position tissue against the tissue thickness compensator  10020  and, in various embodiments, compress the tissue thickness compensator  10020  against the deck surface  10011  of the support portion  10010 , for example. Once the anvil  10060  has been suitably positioned, the staples  10030  can be deployed, as also illustrated in  FIG. 233 . In various embodiments, as mentioned above, the staple-firing sled  10050  can be moved from the proximal end  10001  of the staple cartridge  10000  toward the distal end  10002 , as illustrated in  FIG. 234 . As the sled  10050  is advanced, the sled  10050  can contact the staple drivers  10040  and lift the staple drivers  10040  upwardly within the staple cavities  10012 . In at least one embodiment, the sled  10050  and the staple drivers  10040  can each comprise one or more ramps, or inclined surfaces, which can co-operate to move the staple drivers  10040  upwardly from their unfired positions. In at least one such embodiment, referring to  FIGS. 221-225 , each staple driver  10040  can comprise at least one inclined surface  10042  and the sled  10050  can comprise one or more inclined surfaces  10052  which can be configured such that the inclined surfaces  10052  can slide under the inclined surface  10042  as the sled  10050  is advanced distally within the staple cartridge. As the staple drivers  10040  are lifted upwardly within their respective staple cavities  10012 , the staple drivers  10040  can lift the staples  10030  upwardly such that the staples  10030  can emerge from their staple cavities  10012  through openings in the staple deck  10011 . During an exemplary firing sequence, referring primarily to  FIGS. 227-229 , the sled  10050  can first contact staple  10030   a  and begin to lift the staple  10030   a  upwardly. As the sled  10050  is advanced further distally, the sled  10050  can begin to lift staples  10030   b ,  10030   c ,  10030   d ,  10030   e , and  10030   f , and any other subsequent staples, in a sequential order. As illustrated in  FIG. 229 , the sled  10050  can drive the staples  10030  upwardly such that the legs  10032  of the staples contact the opposing anvil, are deformed to a desired shape, and ejected therefrom the support portion  10010 . In various circumstances, the sled  10030  can move several staples upwardly at the same time as part of a firing sequence. With regard to the firing sequence illustrated in  FIG. 229 , the staples  10030   a  and  10030   b  have been moved into their fully fired positions and ejected from the support portion  10010 , the staples  10030   c  and  10030   d  are in the process of being fired and are at least partially contained within the support portion  10010 , and the staples  10030   e  and  10030   f  are still in their unfired positions. 
     As discussed above, and referring to  FIG. 235 , the staple legs  10032  of the staples  10030  can extend above the deck surface  10011  of the support portion  10010  when the staples  10030  are in their unfired positions. With further regard to this firing sequence illustrated in  FIG. 229 , the staples  10030   e  and  10030   f  are illustrated in their unfired position and their staple legs  10032  extend above the deck surface  10011  and into the tissue thickness compensator  10020 . In various embodiments, the tips of the staple legs  10032 , or any other portion of the staple legs  10032 , may not protrude through a top tissue-contacting surface  10021  of the tissue thickness compensator  10020  when the staples  10030  are in their unfired positions. As the staples  10030  are moved from their unfired positions to their fired positions, as illustrated in  FIG. 229 , the tips of the staple legs can protrude through the tissue-contacting surface  10032 . In various embodiments, the tips of the staple legs  10032  can comprise sharp tips which can incise and penetrate the tissue thickness compensator  10020 . In certain embodiments, the tissue thickness compensator  10020  can comprise a plurality of apertures which can be configured to receive the staple legs  10032  and allow the staple legs  10032  to slide relative to the tissue thickness compensator  10020 . In certain embodiments, the support portion  10010  can further comprise a plurality of guides  10013  extending from the deck surface  10011 . The guides  10013  can be positioned adjacent to the staple cavity openings in the deck surface  10011  such that the staple legs  10032  can be at least partially supported by the guides  10013 . In certain embodiments, a guide  10013  can be positioned at a proximal end and/or a distal end of a staple cavity opening. In various embodiments, a first guide  10013  can be positioned at a first end of each staple cavity opening and a second guide  10013  can be positioned at a second end of each staple cavity opening such that each first guide  10013  can support a first staple leg  10032  of a staple  10030  and each second guide  10013  can support a second staple leg  10032  of the staple. In at least one embodiment, referring to  FIG. 235 , each guide  10013  can comprise a groove or slot, such as groove  10016 , for example, within which a staple leg  10032  can be slidably received. In various embodiments, each guide  10013  can comprise a cleat, protrusion, and/or spike that can extend from the deck surface  10011  and can extend into the tissue thickness compensator  10020 . In at least one embodiment, as discussed in greater detail below, the cleats, protrusions, and/or spikes can reduce relative movement between the tissue thickness compensator  10020  and the support portion  10010 . In certain embodiments, the tips of the staple legs  10032  may be positioned within the guides  10013  and may not extend above the top surfaces of the guides  10013  when the staples  10030  are in their unfired position. In at least such embodiment, the guides  10013  can define a guide height and the staples  10030  may not extend above this guide height when they are in their unfired position. 
     In various embodiments, a tissue thickness compensator, such as tissue thickness compensator  10020 , for example, can be comprised of a single sheet of material. In at least one embodiment, a tissue thickness compensator can comprise a continuous sheet of material which can cover the entire top deck surface  10011  of the support portion  10010  or, alternatively, cover less than the entire deck surface  10011 . In certain embodiments, the sheet of material can cover the staple cavity openings in the support portion  10010  while, in other embodiments, the sheet of material can comprise openings which can be aligned, or at least partially aligned, with the staple cavity openings. In various embodiments, a tissue thickness compensator can be comprised of multiple layers of material. In some embodiments, referring now to  FIG. 217 , a tissue thickness compensator can comprise a compressible core and a wrap surrounding the compressible core. In certain embodiments, a wrap  10022  can be configured to releasably hold the compressible core to the support portion  10010 . In at least one such embodiment, the support portion  10010  can comprise one or more projections, such as projections  10014  ( FIG. 220 ), for example, extending therefrom which can be received within one or more apertures and/or slots, such as apertures  10024 , for example, defined in the wrap  10022 . The projections  10014  and the apertures  10024  can be configured such that the projections  10014  can retain the wrap  10022  to the support portion  10010 . In at least one embodiment, the ends of the projections  10014  can be deformed, such as by a heat-stake process, for example, in order to enlarge the ends of the projections  10014  and, as a result, limit the relative movement between the wrap  10022  and the support portion  10010 . In at least one embodiment, the wrap  10022  can comprise one or more perforations  10025  which can facilitate the release of the wrap  10022  from the support portion  10010 , as illustrated in  FIG. 217 . Referring now to  FIG. 226 , a tissue thickness compensator can comprise a wrap  10222  including a plurality of apertures  10223 , wherein the apertures  10223  can be aligned, or at least partially aligned, with the staple cavity openings in the support portion  10010 . In certain embodiments, the core of the tissue thickness compensator can also comprise apertures which are aligned, or at least partially aligned, with the apertures  10223  in the wrap  10222 . In other embodiments, the core of the tissue thickness compensator can comprise a continuous body and can extend underneath the apertures  10223  such that the continuous body covers the staple cavity openings in the deck surface  10011 . 
     In various embodiments, as described above, a tissue thickness compensator can comprise a wrap for releasably holding a compressible core to the support portion  10010 . In at least one such embodiment, referring to  FIG. 218 , a staple cartridge can further comprise retainer clips  10026  which can be configured to inhibit the wrap, and the compressible core, from prematurely detaching from the support portion  10010 . In various embodiments, each retainer clip  10026  can comprise apertures  10028  which can be configured to receive the projections  10014  extending from the support portion  10010  such that the retainer clips  10026  can be retained to the support portion  10010 . In certain embodiments, the retainer clips  10026  can each comprise at least one pan portion  10027  which can extend underneath the support portion  10010  and can support and retain the staple drivers  10040  within the support portion  10010 . In certain embodiments, as described above, a tissue thickness compensator can be removably attached to the support portion  10010  by the staples  10030 . More particularly, as also described above, the legs of the staples  10030  can extend into the tissue thickness compensator  10020  when the staples  10030  are in their unfired position and, as a result, releasably hold the tissue thickness compensator  10020  to the support portion  10010 . In at least one embodiment, the legs of the staples  10030  can be in contact with the sidewalls of their respective staple cavities  10012  wherein, owing to friction between the staple legs  10032  and the sidewalls, the staples  10030  and the tissue thickness compensator  10020  can be retained in position until the staples  10030  are deployed from the staple cartridge  10000 . When the staples  10030  are deployed, the tissue thickness compensator  10020  can be captured within the staples  10030  and held against the stapled tissue T. When the anvil is thereafter moved into an open position to release the tissue T, the support portion  10010  can be moved away from the tissue thickness compensator  10020  which has been fastened to the tissue. In certain embodiments, an adhesive can be utilized to removably hold the tissue thickness compensator  10020  to the support portion  10010 . In at least one embodiment, a two-part adhesive can be utilized wherein, in at least one embodiment, a first part of the adhesive can be placed on the deck surface  10011  and a second part of the adhesive can be placed on the tissue thickness compensator  10020  such that, when the tissue thickness compensator  10020  is placed against the deck surface  10011 , the first part can contact the second part to active the adhesive and detachably bond the tissue thickness compensator  10020  to the support portion  10010 . In various embodiments, any other suitable means could be used to detachably retain the tissue thickness compensator to the support portion of a staple cartridge. 
     In various embodiments, further to the above, the sled  10050  can be advanced from the proximal end  10001  to the distal end  10002  to fully deploy all of the staples  10030  contained within the staple cartridge  10000 . In at least one embodiment, referring now to  FIGS. 258-262 , the sled  10050  can be advanced distally within a longitudinal cavity  10016  within the support portion  10010  by a firing member, or knife bar,  10052  of a surgical stapler. In use, the staple cartridge  10000  can be inserted into a staple cartridge channel in a jaw of the surgical stapler, such as staple cartridge channel  10070 , for example, and the firing member  10052  can be advanced into contact with the sled  10050 , as illustrated in  FIG. 258 . As the sled  10050  is advanced distally by the firing member  10052 , the sled  10050  can contact the proximal-most staple driver, or drivers,  10040  and fire, or eject, the staples  10030  from the cartridge body  10010 , as described above. As illustrated in  FIG. 258 , the firing member  10052  can further comprise a cutting edge  10053  which can be advanced distally through a knife slot in the support portion  10010  as the staples  10030  are being fired. In various embodiments, a corresponding knife slot can extend through the anvil positioned opposite the staple cartridge  10000  such that, in at least one embodiment, the cutting edge  10053  can extend between the anvil and the support portion  10010  and incise the tissue and the tissue thickness compensator positioned therebetween. In various circumstances, the sled  10050  can be advanced distally by the firing member  10052  until the sled  10050  reaches the distal end  10002  of the staple cartridge  10000 , as illustrated in  FIG. 260 . At such point, the firing member  10052  can be retracted proximally. In some embodiments, the sled  10050  can be retracted proximally with the firing member  10052  but, in various embodiments, referring now to  FIG. 261 , the sled  10050  can be left behind in the distal end  10002  of the staple cartridge  10000  when the firing member  10052  is retracted. Once the firing member  10052  has been sufficiently retracted, the anvil can be re-opened, the tissue thickness compensator  10020  can be detached from the support portion  10010 , and the remaining non-implanted portion of the expended staple cartridge  10000 , including the support portion  10010 , can be removed from the staple cartridge channel  10070 . 
     After the expended staple cartridge  10000  has been removed from the staple cartridge channel, further to the above, a new staple cartridge  10000 , or any other suitable staple cartridge, can be inserted into the staple cartridge channel  10070 . In various embodiments, further to the above, the staple cartridge channel  10070 , the firing member  10052 , and/or the staple cartridge  10000  can comprise co-operating features which can prevent the firing member  10052  from being advanced distally a second, or subsequent, time without a new, or unfired, staple cartridge  10000  positioned in the staple cartridge channel  10070 . More particularly, referring again to  FIG. 258 , as the firing member  10052  is advanced into contact with the sled  10050  and, when the sled  10050  is in its proximal unfired position, a support nose  10055  of the firing member  10052  can be positioned on and/or over a support ledge  10056  on the sled  10050  such that the firing member  10052  is held in a sufficient upward position to prevent a lock, or beam,  10054  extending from the firing member  10052  from dropping into a lock recess defined within the staple cartridge channel. As the lock  10054  will not drop into the lock recess, in such circumstances, the lock  10054  may not abut a distal sidewall  10057  of the lock recess as the firing member  10052  is advanced. As the firing member  10052  pushes the sled  10050  distally, the firing member  10052  can be supported in its upward firing position owing to the support nose  10055  resting on the support ledge  10056 . When the firing member  10052  is retracted relative to the sled  10050 , as discussed above and illustrated in  FIG. 261 , the firing member  10052  can drop downwardly from its upward position as the support nose  10055  is no longer resting on the support ledge  10056  of the sled  10050 . In at least one such embodiment, the surgical staple can comprise a spring  10058 , and/or any other suitable biasing element, which can be configured to bias the firing member  10052  into its downward position. Once the firing member  10052  has been completely retracted, as illustrated in  FIG. 262 , the firing member  10052  cannot be advanced distally through the spent staple cartridge  10000  once again. More particularly, the firing member  10052  can&#39;t be held in its upper position by the sled  10050  as the sled  10050 , at this point in the operating sequence, has been left behind at the distal end  10002  of the staple cartridge  10000 . Thus, as mentioned above, in the event that the firing member  10052  is advanced once again without replacing the staple cartridge, the lock beam  10054  will contact the sidewall  10057  of the lock recess which will prevent the firing member  10052  from being advanced distally into the staple cartridge  10000  once again. Stated another way, once the spent staple cartridge  10000  has been replaced with a new staple cartridge, the new staple cartridge will have a proximally-positioned sled  10050  which can hold the firing member  10052  in its upper position and allow the firing member  10052  to be advanced distally once again. 
     As described above, the sled  10050  can be configured to move the staple drivers  10040  between a first, unfired position and a second, fired position in order to eject staples  10030  from the support portion  10010 . In various embodiments, the staple drivers  10040  can be contained within the staple cavities  10012  after the staples  10030  have been ejected from the support portion  10010 . In certain embodiments, the support portion  10010  can comprise one or more retention features which can be configured to block the staple drivers  10040  from being ejected from, or falling out of, the staple cavities  10012 . In various other embodiments, the sled  10050  can be configured to eject the staple drivers  10040  from the support portion  10010  with the staples  10030 . In at least one such embodiment, the staple drivers  10040  can be comprised of a bioabsorbable and/or biocompatible material, such as Ultem, for example. In certain embodiments, the staple drivers can be attached to the staples  10030 . In at least one such embodiment, a staple driver can be molded over and/or around the base of each staple  10030  such that the driver is integrally formed with the staple. U.S. patent application Ser. No. 11/541,123, entitled SURGICAL STAPLES HAVING COMPRESSIBLE OR CRUSHABLE MEMBERS FOR SECURING TISSUE THEREIN AND STAPLING INSTRUMENTS FOR DEPLOYING THE SAME, filed on Sep. 29, 2006, now U.S. Pat. No. 7,794,475, is hereby incorporated by reference in its entirety. 
     In various circumstances, further to the above, a compressible tissue thickness compensator can move, twist, and/or deflect relative to the underlying rigid support portion of a staple cartridge. In various embodiments, the support portion, and/or any other suitable portion of the staple cartridge, can comprise one or more features configured to limit relative movement between the tissue thickness compensator and the support portion. As described above, at least a portion of the staples  10030  can extend above the deck surface  10011  of the support portion  10010  wherein, in certain circumstances, referring now to  FIGS. 263 and 264 , lateral forces applied to a tissue thickness compensator  10120 , for example, can be resisted by the staples  10030  and/or the cleats  10013  extending from the support portion  10010 , for example. In various circumstances, the staples  10030  may tilt and/or bend within the staple cavities  10012  while resisting the lateral movement of the tissue thickness compensator  10120  wherein, in various embodiments, the staple cavities  10012  and the staples  10030  can be sized and configured to maintain the relative alignment between the legs  10032  of the staples  10030  and the forming pockets  10062  in the opposing anvil  10060  such that the staples  10000  are properly formed during the staple forming process. In various embodiments, the staples  10030  and/or the cleats  10013  can be configured to prevent or at least limit lateral distortion within the tissue thickness compensator  10020 , as illustrated in  FIG. 264 . In at least one such embodiment, the staples  10030  and/or cleats  10013 , for example, can be configured to stiffen, or limit the lateral and/or longitudinal movement of, a first, or tissue-contacting, surface  10021  of the tissue thickness compensator relative to a second, or bottom, surface  10029 . In various embodiments, a staple cartridge, and/or a staple cartridge channel in which the staple cartridge is positioned, can comprise at least one distortion minimizing member which can extend upwardly to limit the lateral and/or longitudinal movement, or distortion, of a tissue thickness compensator. A wrap at least partially surrounding a tissue thickness compensator, as discussed above, may also prevent, or at least limit, the lateral and/or longitudinal movement, or distortion, of the tissue thickness compensator. 
     In various embodiments, referring again to  FIGS. 263 and 264 , a tissue thickness compensator, such as tissue thickness compensator  10120 , for example, can comprise a core  10128  and a skin  10122 . The skin  10122  and the compressible core  10128  can be comprised of different materials or, alternatively, of the same material. In either event, the skin  10122  can have a higher density than the core  10128 . In circumstances where the skin  10122  comprises the top of the tissue thickness compensator  10120 , the tips of the staple legs  10032  can be embedded in the skin  10122 . In embodiments wherein a skin comprises the bottom of the tissue thickness compensator  10120 , the staple legs  10032  can extend through the skin and into the core. In either event, the skin of the tissue thickness compensator can assist in holding the staple legs  10032  in alignment with the forming pockets  10062  of the anvil  10060 . In various embodiments, the skin  10122  can comprise a density which is approximately 10% greater than the density of the core  10128 , approximately 20% greater than the density of the core  10128 , approximately 30% greater than the density of the core  10128 , approximately 40% greater than the density of the core  10128 , approximately 50% greater than the density of the core  10128 , approximately 60% greater than the density of the core  10128 , approximately 70% greater than the density of the core  10128 , approximately 80% greater than the density of the core  10128 , approximately 90% greater than the density of the core  10128 , and/or approximately 100% greater than the density of the core  10128 , for example. In various embodiments, the skin  10122  can comprise a density which is more than the density of the core  10128  and less than twice the density of the core  10128 , for example. In various embodiments, the skin  10122  can comprise a density which is over twice the density of the core  10128 , for example. In various embodiments, further to the above, the skin  10122  and the core  10128  can be formed, or manufactured, simultaneously. In at least one such embodiment, a fluid comprising any suitable material disclosed herein can be poured into a dish or mold and, while the fluid solidifies, the fluid can form a skin, or layer, which has a higher density than the remainder of the material. In various embodiments, multiple layers within a material can be formed by utilizing a process in which one or more subsequent layers of material are poured onto a previously cured layer. In certain embodiments, two or more layers can be bonded to each other with an adhesive, for example. In some embodiments, two or more layers can be attached to each other by one or more fasteners and/or one or more mechanical interlocking features, for example. In at least one such embodiment, adjacent layers can be connected together by one or more dovetail joints, for example. In certain embodiments, the skin can comprise a sealed surface which can prevent, or at least limit, the flow of fluid therethrough. In certain other embodiments, the skin can comprise an open cell porous structure, for example. 
     In various embodiments, further to the above, the skin can be cut off of the tissue thickness compensator. In at least one embodiment, the tissue thickness compensator can be cut from a larger block of material such that the tissue thickness compensator does not comprise a skin. In at least one such embodiment, the tissue thickness compensator can be comprised of a homogenous, or at least substantially homogeneous, material, comprising large pores, for example. 
     In various embodiments, a staple cartridge can comprise a plurality of staple cavities each containing a staple positioned therein wherein the staple cavities can be arranged in a plurality of rows, and wherein an anvil positioned opposite the staple cartridge can comprise a plurality of forming pockets which correspond to the staple cavities in the staple cartridge. Stated another way, the anvil can comprise a plurality of forming pocket rows wherein each forming pocket can be positioned opposite a staple cavity in the staple cartridge. In various embodiments, each forming pocket can comprise two forming cups configured to receive the staple legs  10032  of a staple  10030  wherein each forming cup is configured to receive a staple leg  10032  and form or curl the staple leg  10032  toward the other staple leg  10032 , for example. In various circumstances, the legs  10032  may miss or not properly enter into the forming cups and, as a result, the staple legs  10032  may become malformed during the firing sequence. In various embodiments described herein, an anvil can comprise an array, or grid, of forming pockets which are each configured to receive and form a staple leg. In at least one such embodiment, the array of forming pockets can comprise a quantity of forming pockets that exceeds the quantity of staples contained within the staple cartridge. In at least one embodiment, a staple cartridge can comprise six longitudinal rows of staple cavities, for example, wherein the anvil can comprise six rows of forming pockets aligned with the six rows of staple cavities and, in addition, forming pockets positioned intermediate the rows of forming pockets. For example, on one side of the anvil, the anvil can comprise a first row of forming pockets which can be positioned over a first row of staple cavities, a second row of forming pockets which can be positioned over a second row of staple cavities that is adjacent to the first row of staple cavities, and, in addition, a row of forming pockets positioned intermediate the first row of forming pockets and the second row of forming pockets. In various embodiments, referring now to  FIGS. 276-279 , an anvil  10260  can comprise six rows of forming pockets  10261  which can be configured to be placed over six corresponding rows of staple cavities in the staple cartridge  10200 . In at least one such embodiment, rows of intermediate forming pockets  10262  can be positioned intermediate and/or adjacent to the rows of forming pockets  10261 . In certain embodiments, referring now to  FIGS. 277, 278, and 280 , each forming pocket  10261  and  10262  can comprise two forming cups, wherein each forming cup can comprise a distal portion  10263  which can be configured to form or curl a staple leg  10032  proximally and a proximal portion  10264  which can be configured to form or curl a staple leg  10032  distally. In various other circumstances, the staples  10030  can be formed in a variety of other ways. For example, a staple  10030  can be formed such that one leg  10032  is formed outwardly and the other leg  10032  is formed inwardly ( FIG. 281 ), or such that both legs  10032  are formed outwardly ( FIG. 282 ) depending on, one, which forming cups that the staple legs  10032  enter into and/or, two, whether the legs  10032  enter into the proximal portion  10263  or the distal portion  10064  of each forming cup, for example. 
     In various embodiments, further to the above, each forming pocket  10261  and/or forming pocket  10262  can comprise a triangular or diamond-like shape, for example. In at least one embodiment, each distal portion  10263  and/or each proximal portion  10264  of the forming pockets can comprise a triangular shape wherein, in at least one such embodiment, the triangular shapes of the distal portions  10263  and the proximal portions  10264  can be arranged such that they have vertices pointing in opposite directions. In certain embodiments, an anvil can comprise an array of substantially square forming pockets, for example. In at least one such embodiment, the forming surface of each square forming pocket can comprise an arcuate surface that extends between the sides of the square. In some embodiments, an anvil can comprise an array of circular or spherical dimples, for example. In various embodiments, further to the above, the forming pockets  10261  can be positioned along one or more lines and, similarly, the forming pockets  10262  can also be positioned along one or more lines. In various other embodiments, the forming pockets  10261  and/or the forming pockets  10262  can be arranged in one or more circular rows. In at least one such embodiment, the forming pockets  10261  can be arranged along a primary circumference and the forming pockets  10262  can be arranged along a different circumference. In various embodiments, the primary circumference and the different circumference can be concentric, or at least substantially concentric. In certain embodiments, the forming pockets  10262  can be arranged along an inner circumference positioned radially inwardly with respect to the primary circumference and/or an outer circumference positioned radially outwardly with respect to the primary circumference, for example. In various embodiments, the primary circumference can be defined by a primary diameter, the inner circumference can be defined by an inner diameter, and the outer circumference can be defined by an outer diameter. In at least one such embodiment, the inner diameter can be shorter than the primary diameter and the outer diameter can be longer than the primary diameter. 
     In various embodiments, as described above, an anvil can be moved from an open position to a closed position in order to compress tissue against the tissue thickness compensator of a staple cartridge, such as tissue thickness compensator  10020 , for example. In various circumstances, the tissue thickness compensator can be positioned adjacent to the support portion of the staple cartridge prior to the tissue thickness compensator being positioned relative to the tissue. In certain embodiments, the tissue thickness compensator  10020  can be in a position in which it abuts the support portion  10018  prior to the anvil being moved into its closed position. In certain other embodiments, the tissue thickness compensator  10020  can be in a position in which a gap is present between the tissue thickness compensator  10020  and the support portion  10018 . In at least one such embodiment, the anvil can displace the tissue and the tissue thickness compensator  10020  downwardly until the tissue thickness compensator  10020  abuts the support portion  10018  wherein, at such point, the anvil can be moved into is closed position and generate compression within the tissue. In the event that a surgeon is not satisfied with the positioning of the tissue between the anvil and the staple cartridge, the surgeon can open the anvil, adjust the position of the anvil and the staple cartridge, and close the anvil once again. Owing to such positioning and re-positioning of the staple cartridge relative to the tissue, in various circumstances, the distal end of the tissue thickness compensator  10020  may become dislodged from the support portion  10010 , for example. In some such circumstances, the distal end of the tissue thickness compensator  10020  can contact the tissue and peel away from, or roll relative to, the support portion  10010 . In various embodiments, as described in greater detail below, a staple cartridge can comprise one or more features configured to releasably retain a tissue thickness compensator to an underlying support portion of the staple cartridge 
     In various embodiments, referring now to  FIG. 265 , a staple cartridge  10300  can comprise a support portion  10310 , a tissue thickness compensator  10320  supported by the support portion  10310 , and a distal end  10302  which includes a nose  10303  configured to releasably hold a distal end  10325  of the tissue thickness compensator  10320  in position. In at least one embodiment, the nose  10303  can comprise a slot  10305  configured to receive the distal end  10325  of the tissue thickness compensator  10320 . In various embodiments, the distal end  10325  can be compressed, or wedged, within the slot  10305  such that the distal end  10325  can be held in place as the staple cartridge  10300  is positioned relative to the tissue. In at least one such embodiment, the slot  10305  can be oriented in a direction which is parallel, or at least substantially parallel, to the deck surface  10311  of the support portion  10310 . In various embodiments, the slot  10305  can be horizontal with respect to the deck surface  10311 . In various other embodiments, referring now to  FIG. 266 , a staple cartridge  10400  can comprise a support portion, a tissue thickness compensator  10420  supported by support portion, and a distal end  10402  which includes a nose  10403  configured to releasably hold the distal end  10425  of the tissue thickness compensator  10420  in position. In at least one embodiment, the distal end  10425  can comprise a projection extending therefrom and the nose  10403  can comprise a vertical slot  10405  configured to receive the projection of the distal end  10425 . In various embodiments, the distal end  10425 , and/or the projection extending therefrom, can be compressed, or wedged, within the slot  10405  such that the distal end  10425  can be held in place as the staple cartridge  10400  is positioned relative to the tissue. In certain embodiments, the tissue thickness compensator  10420  can comprise a slot, such as slot  10429 , for example, which can be configured to receive at least a portion of the nose  10403  therein. In at least one embodiment, the slot  10405  can be oriented in a direction which is perpendicular, or at least substantially perpendicular, to the deck surface  10411  of the support portion. In various embodiments, referring now to  FIG. 267 , a staple cartridge  10500  can comprise a support portion, a tissue thickness compensator  10520  supported by the support portion, and a distal end  10502  which includes a nose configured to releasably hold the distal end  10525  of the tissue thickness compensator  10520  in position. In at least one embodiment, the nose can comprise a vertical slot  10505  configured to receive the distal end  10525  of the tissue thickness compensator  10520 . In various embodiments, the distal end  10525  can be compressed, or wedged, within the slot  10505  such that the distal end  10525  can be held in place as the staple cartridge  10500  is positioned relative to the tissue. 
     In various embodiments, referring again to  FIG. 265 , the tissue thickness compensator  10320  can comprise a top surface  10324  which can be positioned above the top surface  10304  of the nose  10303 . Another exemplary embodiment in which the top surface of a tissue thickness compensator is positioned above the nose of the staple cartridge is illustrated in  FIG. 238 , wherein the top surface  10721  of the tissue thickness compensator  10720  is positioned above the top surface  10004  of the nose  10003 , for example. In use, referring once again to  FIG. 265 , tissue can slide over the top surface  10304  of the nose  10303  and, in some circumstance, the tissue can contact the distal end  10325  of the tissue thickness compensator  10320  and can apply a force to the tissue thickness compensator  10320  tending to peel the tissue thickness compensator  10320  away from the support portion  10310 . In the embodiments described herein, this peel force can be resisted by the portion of the distal end  10325  wedged within the nose  10303 . In any event, once the tissue has been suitably positioned relative to the staple cartridge  13000 , an anvil can be rotated into a closed position to compress the tissue and the tissue thickness compensator  10320  against the support portion  10310 . In at least one such embodiment, the anvil can be rotated into a position in which the anvil contacts the top surface  10304  of the nose  10303  and, as a result, the anvil can be prevented from rotating further. In various circumstances, owing to the top surface  10324  of the tissue thickness compensator  10320  being positioned above the top surface  10304  of the nose  10303 , the top surface  10324  can be pushed downwardly toward the support portion  10310  as the anvil is being closed and, in some circumstances, the top surface  10324  can be pushed below the top surface  10304  of the nose  10303 , for example. After the staples contained within the staple cartridge  10300  have been deployed and the tissue thickness compensator  10320  has been incised, as described herein, the support portion  10310  and the nose  10303  can be moved away from the tissue thickness compensator  10320  such that the distal end  10325  of the tissue thickness compensator  10320  can slide out of the slot  10305 . 
     As described above, an anvil, such as anvil  10060 , for example, can be rotated into a closed position in which the anvil  10060  contacts the top nose surface  10004  of a staple cartridge, such as staple cartridge  10000 , for example. Once the anvil has reached its closed position, the amount in which a tissue thickness compensator, such as tissue thickness compensator  10020 , for example, is compressed will depend on, among other things, the uncompressed thickness, or height, of the tissue thickness compensator and the thickness of the tissue. Referring now to  FIGS. 236 and 237 , a tissue thickness compensator  10920  can comprise a top surface which is flush, or at least substantially flush, with the top surface  10004  of the nose  10003 . In such embodiments, the top surface of the tissue thickness compensator  10920  can be pushed below the top surface  10004  of the nose  10003 . Referring now to  FIGS. 241 and 242 , a tissue thickness compensator, such as tissue thickness compensator  10820 , for example, can comprise a top surface  10821  which is positioned below the top nose surface  10004  prior to the tissue thickness compensator  10820  being compressed by the tissue T and anvil  10060 . In the circumstances where the tissue T is relatively thin, as illustrated in  FIGS. 239 and 240 , the tissue thickness compensator  10920  may undergo relatively little compression. Referring now to  FIGS. 241 and 242 , the tissue thickness compensator  10820  may undergo a larger compression when the tissue T is relatively thicker. In the circumstances where the tissue T has both thin sections and thicker sections, as illustrated in  FIGS. 243 and 244 , the tissue thickness compensator  10820  may be compressed a larger amount when it is positioned under the thicker tissue T and a lesser amount when it is positioned under the thinner tissue T, for example. In this way, as described above, the tissue thickness compensator can compensate for different tissue thicknesses. 
     In various embodiments, referring now to  FIGS. 268-270 , a surgical stapling instrument can comprise, one, a cartridge channel  16670  configured to receive a staple cartridge  16600  and, two, an anvil  16660  pivotably coupled to the cartridge channel  16670 . The staple cartridge  16600  can comprise a support portion  16610  and a tissue thickness compensator  16620  wherein a distal end  16625  of the tissue thickness compensator  16620  can be releasably held to the support portion  16610  by a nose  16603  at the distal end  16602  of the staple cartridge  16600 . In at least one embodiment, the nose  16603  can comprise a slot  16605  and can be comprised of a flexible material. In use, referring primarily to  FIG. 269 , the nose  16603  can be flexed downwardly in order to expand the opening of slot  16605 . In certain embodiments, the nose  16603  can comprise notches or cut-outs  16606  which can be configured to permit the nose  16603  to flex downwardly. In any event, in various circumstances, the expanded opening of the slot  16605  can facilitate the insertion of the distal end  16625  of the tissue thickness compensator  16620  into the slot  16605 . Once the tissue thickness compensator  16620  has been suitably positioned, the nose  16603  can be released and, owing to the resiliency of the material comprising the nose  16603 , the nose  16603  can return, or at least substantially return, to its unflexed condition and trap the distal end  16625  of the tissue thickness compensator  16620  against the deck surface  16611 , as illustrated in  FIG. 270 . In use, similar to the above, the distal end  16625  can be pulled out of the slot  16605  when the support portion  16610  is moved away from the stapled tissue. In various circumstances, the flexible nose  16603  can be configured to deflect as the tissue thickness compensator  16620  is detached from the support portion  16610 . In various embodiments, referring again to  FIG. 270 , the tissue thickness compensator  16620  can comprise a top surface  16621  which is aligned, or at least substantially aligned, with a top surface  16604  of the nose  16603 . 
     In various embodiments, referring to  FIG. 271 , a surgical stapling instrument can comprise, one, a channel  10770  configured to receive a staple cartridge  10700  and, two, an anvil  10760  rotatably coupled to the channel  10770 . The staple cartridge  10700  can comprise a support portion  10710  and a tissue thickness compensator  10720 . In various embodiments, the tissue thickness compensator  10720  can be held in position by a nose sock  10703  which can be slid over the support portion  10710 . In at least one embodiment, referring primarily to  FIG. 272 , the nose sock  10703  can comprise one or more side slots  10707  which can be configured to removably receive one or more attachment rails extending along the support portion  10710 , for example. In various embodiments, the tissue thickness compensator  10720  can be positioned intermediate the side slots  10707 . In certain embodiments, the nose sock  10703  can further comprise a distal end  10702  and a cavity  10706  defined in the distal end  10702  wherein the cavity  10706  can also be configured to receive at least a portion of the support portion  10710 , for example, therein. In use, the nose sock  10703  can be slid onto the support portion  10710  in a distal to proximal direction. In various embodiments, the tissue thickness compensator  10720  can be removably mounted to the nose sock  10703  such that, after staples have been fired through the tissue thickness compensator  10720 , the tissue thickness compensator  10720  can detach from the nose sock  10703  as the support portion  10710  and the nose sock  10703  are moved away from the tissue thickness compensator  10720 . In various embodiments, the top surface  10721  of the tissue thickness compensator  10720  can be positioned below the top surface  10704  of the nose  10703 . 
     In various embodiments, referring now to  FIGS. 273 and 274 , a surgical stapling instrument can comprise, one, a staple cartridge channel  11070  configured to receive a staple cartridge  11000  and, two, an anvil  11060  rotatably coupled to the channel  11070 . The staple cartridge  11000  can comprise a support portion  11010  and a tissue thickness compensator  11020 . In various embodiments, the tissue thickness compensator  11020  can be held in position by a one or more longitudinal rails  11019  extending from the deck  11011  of the support portion  11010 . In at least one embodiment, the longitudinal rails  11019  can be embedded within the tissue thickness compensator  11020 . In certain embodiments, referring primarily to  FIG. 274 , the tissue thickness compensator  11020  can comprise a longitudinal recess  11029  which can be configured to receive the longitudinal rails  11019 . In at least one such embodiment, the recess  11029  can be sized and configured to receive the rails  11019  in a press-fit arrangement, for example. Such features, further to the above, can be configured to prevent, or at least limit, relative lateral movement between the tissue thickness compensator  11020  and the support portion  11010  and, in addition, limit the pre-mature release of the tissue thickness compensator  11020  from the support portion  11010 , for example. In various embodiments, referring now to  FIG. 275 , a surgical stapling instrument can comprise, one, a staple cartridge channel  11170  configured to receive a staple cartridge  11100  and, two, an anvil  11160  rotatably coupled to the channel  11170 . The staple cartridge  11100  can comprise a support portion  11110  and a tissue thickness compensator  11120 . In various embodiments, the tissue thickness compensator  11120  can be held in position by one or more longitudinal rows of spikes, or teeth,  11119  extending from the deck  11111  of the support portion  11110 . In at least one embodiment, the longitudinal rows of spikes  11119  can be embedded within the tissue thickness compensator  11120 . 
     With regard to the embodiment illustrated in  FIG. 273 , further to the above, the tissue thickness compensator  11020  of the staple cartridge  11000  can be progressively released from the support portion  11010  as the staples are ejected from the staple cavities  10012  defined therein. More particularly, further to the above, the staples positioned in the staple cavities  10012  can be ejected sequentially between the proximal end  11001  of the staple cartridge  11000  and the distal end  11002  of the staple cartridge  11000  such that, as the staples are being ejected, the staples can apply an upward biasing force to the tissue thickness compensator  11020  which acts to push the tissue thickness compensator  11020  off of the rails  11019 . In such circumstances, the proximal end  11006  of the tissue thickness compensator  11020  can be released from the support portion  11010  as the staples are ejected from the proximal-most staple cavities  10012 . The tissue thickness compensator  11020  can then be progressively released from the support portion  11010  as the staples are progressively ejected from the support portion  11010  between the proximal end  11001  and the distal end  11002  of the staple cartridge  11000 . When the staples positioned within the distal-most staple cavities  10012  are ejected from the support portion  11010 , the distal end  11007  of the tissue thickness compensator  11020  can be released from the support portion  11010 . With regard to the embodiment illustrated in  FIG. 275 , the tissue thickness compensator  11120  can be progressively released from the spikes  1119  extending from the support portion  11110  as the staples are progressively ejected from the staple cartridge between the proximal end  11101  and the distal end  11102 . 
     As discussed above, a tissue thickness compensator can be progressively released from the support portion of a staple cartridge as the staples are progressively ejected from the support portion and contact the tissue thickness compensator. In various embodiments, the legs of the staple, such as staple legs  10032 , for example, may be able to pass through the tissue thickness compensator without releasing the tissue thickness compensator from the support portion. In such embodiments, the tissue thickness compensator may remain engaged with the support portion until the bases of the staples, such as bases  10031 , contact the tissue thickness compensator and push it upwardly. In various embodiments, however, cleats and/or other retention features extending from the support portion, for example, may oppose the release of the tissue thickness compensator from the support portion. In certain embodiments, as described in greater detail below, a support portion can comprise retention features which can be configured to progressively release a tissue thickness compensator from the support portion as the staples are progressively fired from the staple cartridge. Referring now to  FIG. 283 , a staple cartridge, such as staple cartridge  11200 , for example, can comprise a support portion  11210  including retention features  11213  which can be configured to releasably hold a tissue thickness compensator  11220  ( FIG. 284 ) to the support portion  11210 . In various embodiments, the retention features  11213  can be positioned at the ends of each staple cavity  11212 , for example, wherein each retention feature  11213  can comprise a guide groove  11216  defined therein which is configured to slidably receive a staple leg  10032  of a staple  10030 . In such embodiments, both the staple legs  10032  and the retention features  11213  can be configured to releasably retain the tissue thickness compensator  11220  to the support portion  11210 . In use, referring now to  FIG. 284 , staple drivers  10040  contained within the support portion  11210  can be driven upwardly by a sled  10050 , as described above, wherein the staple drivers  10040  can be configured to contact the retention features  11213 , at least partially detach the retention features  11213  from the support portion  11210 , and displace the retention features  11213  outwardly and away from the staples  10030  and the staple cavities  11212 . When the retention features  11213  are detached from the support portion  11210  and/or displaced outwardly, as illustrated in  FIG. 284 , the retention features  11213  may no longer be able to retain the tissue thickness compensator  11220  to the support portion  11210  and, as a result, the tissue thickness compensator  11220  can be released from the support portion  11210 . Similar to the above, the tissue thickness compensator  11220  can be progressively released from the support portion  11210  as the staples  10030  are progressively ejected from the staple cartridge toward an anvil, such as anvil  11260 , for example. In various embodiments, the staple drivers  10040  may contact the retention features  11213  when the top surfaces of the staple drivers  10040  become co-planar, or at least substantially co-planar, with the deck surface  11211  of the support portion  11210 , for example. In such embodiments, the tissue thickness compensator  11220  may be released from the support portion  11210  at the same time as and/or just before the staples  10030  are formed to their fully-formed, or fully-fired, configuration. In at least one such embodiment, referring primarily to  FIG. 285 , the drivers  10040  can be overdriven such that they are pushed above the deck surface  11211  to fully form the staples  10030  and, during the process of being overdriven, break the retention features  11213  away from the support portion  11210 . In various embodiments, referring again to  FIG. 284 , the retention features  11213  may extend over, or overhang, into the staple cavities  11212  prior to being detached or displaced outwardly such that the drivers  10040  can contact the retention features  11213  just as the drivers  10040  reach the deck surface  11211 . In any event, once the tissue thickness compensator  11220  has been released from the support portion  11210 , referring now to  FIG. 285 , the support portion  11210  can be moved away from the implanted tissue thickness compensator  11220 . 
     As described above, a compressible tissue thickness compensator of a staple cartridge can be progressively released from a support portion, or cartridge body, of the staple cartridge as the staples are fired, or deployed, from the staple cartridge. In various circumstances, such a release can comprise a progressive loosening of the tissue thickness compensator from the support portion wherein, in some circumstances, a complete detachment of the tissue thickness compensator from the support portion may not occur until the anvil is opened and the support portion is moved away from the implanted tissue thickness compensator. In various embodiments, referring now to  FIG. 289 , a staple cartridge, such as staple cartridge  11300 , for example, can comprise a tissue thickness compensator  11320  which is releasably retained to a support portion  11310 . In at least one embodiment, the support portion  11310  can comprise a plurality of retention members  11313  extending therefrom which are configured to releasably compress and hold the longitudinal sides of the tissue thickness compensator  11320  to the support portion  11310 . In at least one such embodiment, each retention member  11313  can comprise an inwardly-facing channel or slot  11316  which can be configured to receive the longitudinal sides of the tissue thickness compensator  11320  therein. In various circumstances, a plurality of retention members  11313  can extend along a first longitudinal side of the support portion  11310  and a plurality of retention members  11313  can extend along a second longitudinal side of the support portion  11310  wherein, in certain circumstances, the retention members  11313  can be configured to prevent, or at least limit, relative lateral movement between the tissue thickness compensator  11320  and the support portion  11310  and, in addition, prevent, or at least limit, the premature release of the tissue thickness compensator  11320  from the support portion  11310 . In various embodiments, the retention members  11313  can be integrally formed with the support portion  11310  and, in at least one embodiment, referring to  FIG. 290 , the retention members  11313  can be configured to detach, or at least partially detach, from the support portion  11310  in order to allow the tissue thickness compensator  11320  to detach from the support portion  11310 , as illustrated in  FIG. 291 , for example. In certain embodiments, an anvil, such as anvil  11360 , for example, can be configured to compress the tissue thickness compensator  11320  and, in response to pressure generated within the tissue thickness compensator  11320 , the tissue thickness compensator  11320  can expand laterally to at least partially detach, or disengage, the retention members  11313  from the tissue thickness compensator  11320 . In various embodiments, the advancement of a knife member, discussed above, through the anvil  11360  and the staple cartridge  11300  can deploy the staples contained therein and, simultaneously, squeeze the anvil  11360  and the staple cartridge  11300  closer to one another which can apply an added compressive pressure to the tissue thickness compensator  11320  and thereby cause the retention members  11313  to sequentially detach as the knife member passes through the staple cartridge  11300 . 
     In various embodiments, referring now to  FIGS. 292-294 , a staple cartridge, such as staple cartridge  11400 , for example, can comprise a tissue thickness compensator  11420  removably attached to a support portion  11410 . In at least one embodiment, the staple cartridge  11400  can comprise one or more retainer bars  11413  which can be configured to hold the longitudinal sides of the tissue thickness compensator  11420  to the deck surface  11411 . In at least one such embodiment, each retainer bar  11413  can comprise opposing arms  11418  which can define a channel  11416  therebetween. In such embodiments, one of the arms  11418  can be configured to extend over the tissue thickness compensator  11420  and the other arm  11418  can be configured to extend under a lip  11419  extending from the support portion  11410 . Referring primarily to  FIG. 292 , the channel  11416  of each retainer bar  11413  can be sized and configured to apply a compressive force to the longitudinal sides of the tissue thickness compensator  11420  prior to the staple cartridge  11400  being used. During use, referring primarily to  FIG. 293 , the staple cartridge  11400  can be positioned within a staple cartridge channel and, once the staple cartridge  11400  has been suitably positioned, an anvil, such as anvil  11460 , for example, can be moved into a position in which it can compress the tissue thickness compensator  11420 . Similar to the above, the thickness tissue compensator  11420 , when compressed, can expand laterally, or outwardly, and, as a result, detach the retainer bars  11413  from the staple cartridge  11400 . In certain other embodiments, the closing of the anvil  11460  may not detach, or may not completely detach, the retainer bars  11413  from the staple cartridge. In at least one such embodiment, the advancement of a firing bar, described above, through the staple cartridge  11400  can deploy the staples  10030  from the support portion  11410  and, simultaneously, squeeze the anvil  11460  and the staple cartridge  11400  closer together to apply a compressive force to the tissue thickness compensator  11420  that is sufficient to cause the tissue thickness compensator  11420  to expand laterally and detach the retainer bars  11413  from the staple cartridge  11400 . Once the retainer bars  11413  have been detached from the staple cartridge  11400 , referring to  FIG. 294 , the support portion  11410  can be moved away from the implanted tissue thickness compensator  11420  and removed from the surgical site. In certain alternative embodiments, referring now to  FIG. 295 , a staple cartridge  11400 ′ can comprise retainer bars  11413 ′ which, similar to the above, can comprise arms  11418 ′ extending therefrom. In at least one such embodiment, each of the arms  11418 ′ can comprise a wedge-lock bevel  11417 ′ which can be configured to releasably latch the retainer bars  11413 ′ to the staple cartridge  11400 ′. More particularly, in at least one embodiment, the support portion  11410 ′ of the staple cartridge  11400 ′ can comprise undercuts  11419 ′ which, in co-operation with the wedge-lock bevels  11417 ′, can be configured to releasably retain the retainer bars  11413 ′ to the staple cartridge  11400  and inhibit the tissue thickness compensator  11420  from being prematurely detached from the support portion  11410 ′. During use, similar to the above, the retainer bars  11413 ′ can be detached from the staple cartridge  11400 ′ when a sufficient compressive force is applied to the tissue thickness compensator  11420 , for example. 
     In various circumstances, as described above and referring again to  FIGS. 259 and 260 , the sled  10050  of the staple cartridge  10000  and the firing member  10052  of a surgical stapling instrument can be moved from the proximal end  10001  of the staple cartridge  10000  to the distal end  10002  ( FIG. 219 ) of the staple cartridge  10000  in order to deploy the staples  10030  from the support portion  10010 . In at least one such circumstance, each staple  10030  can be moved from an unfired position to a fired position and ejected from the support portion  10010  to capture the entirety of the tissue thickness compensator  10020  against the tissue positioned between the anvil  10060  and the staple cartridge  10000 . In certain circumstances, a surgeon may not need to fire all of the staples  10030  from the staple cartridge  10000  and the surgeon may stop the progression of the sled  10050  and the firing bar  10052  at a point located intermediate the proximal end  10001  and the distal end  10002  of the staple cartridge  10000 . In such circumstances, the tissue thickness compensator  10020  may only be partially implanted to the tissue T and, in order to detach the unimplanted portion of the tissue thickness compensator  10020  from the support portion  10010 , the surgeon can pull the support portion  10010  away from the partially implanted tissue thickness compensator  10020  such that the unimplanted portion peels or pulls off of the support portion  10010 . While such embodiments are suitable in various circumstances, an improvement is illustrated in  FIGS. 300-302  wherein a tissue thickness compensator, such as tissue thickness compensator  11520  of staple cartridge  11500 , for example, can comprise a plurality of connected segments which can be configured to detach from one another. In at least one such embodiment, the tissue thickness compensator  11520  can comprise a first, or proximal-most, segment  11520   a , a second segment  11520   b  removably connected to the first segment  11520   a , a third segment  11520   c  removably connected to the second segment  11520   b , a fourth segment  11520   d  removably connected to the third segment  11520   c , and a fifth segment  11520   e  removably connected to the fourth segment  11520   d , for example. In various embodiments, the tissue thickness compensator  11520  can comprise at least one thin section  11529  positioned intermediate any two adjacent segments  11520   a - 11520   e  which can be configured to define a pre-determined rupture or separation point in which the tissue thickness compensator segments can separate from one another. In certain embodiments, a tissue thickness compensator can include any suitable arrangement of perforations, thin sections, and/or any other means for creating a separation point within the tissue thickness compensator. Referring primarily to  FIG. 301 , an anvil  11560  is illustrated in a closed position and the firing member  10052  is illustrated as having been partially advanced through the staple cartridge  11500  such that the staples  10030  underlying the first segment  11520   a , the second segment  11520   b , and the third segment  11520   c  have been fired to capture the tissue thickness compensator  11520  against the tissue T. In such a position, the firing member  10052  has not yet been advanced to deploy the staples  10030  underlying the fourth segment  11520   d  and the fifth segment  11520   e , for example. Referring now to  FIG. 302 , the anvil  11560  has been moved into an open position and the support portion  11510  of the staple cartridge  11500  has been moved away from the portion of the tissue thickness compensator  11520  that has been implanted. As illustrated in  FIG. 302 , the thin section  11529  ( FIG. 300 ) located intermediate the third segment  11520   c  and the fourth segment  11520   d  has allowed the unimplanted portion of the tissue thickness compensator  11520  to separate from the implanted portion. 
     In various embodiments, further to the above, a staple cartridge can comprise a plurality of fasteners configured to releasably hold a tissue thickness compensator to a support portion of the staple cartridge. In certain embodiments, the support portion can comprise a plurality of apertures defined in the deck surface, for example, wherein the fasteners can extend through the tissue thickness compensator and can be releasably retained in the support portion apertures. In use, the fasteners can be progressively released from the support portion as the staples are progressively ejected from the support portion. In at least one such embodiment, the fasteners can be implanted with the tissue thickness compensator and, in at least one embodiment, the fasteners can be comprised of at least one bioabsorbable material, for example. In certain embodiments, the fasteners can detach from the support portion after the tissue thickness compensator has been at least partially implanted and as the support portion is moved away from the implanted tissue thickness compensator. In various embodiments, referring now to  FIGS. 323-325 , a staple cartridge, such as staple cartridge  11600 , for example, can comprise a tissue thickness compensator  11620  releasably mounted to a support portion  11610  by a plurality of fasteners  11613 . Each fastener  11613  can comprise a first end  11618  embedded within and/or otherwise engaged with the tissue thickness compensator  11620 , a second end  11618  engaged with the support portion  11610 , and a connector  11616  which connects the first end  11618  to the second end  11618 . In various embodiments, the fasteners  11613  can extend through a knife slot  11615  defined in the support portion  11610 . In use, the firing member  10052 , described above, can move a knife edge through the knife slot  11615  in the support portion  11610  and incise the fasteners  11613  in order to release the tissue thickness compensator  11620  from the support portion  11610 . In at least one such embodiment, the firing bar  10052  can be advanced from a proximal end  11601  of the staple cartridge  11600  to a distal end  11602  of the staple cartridge  11600  in order to, one, advance the sled  10050  distally and progressively fire the staples  10030 , as discussed above, and, two, progressively incise and/or break the fasteners  11613  to progressively release the tissue thickness compensator  11620  from the support portion  11610 . In certain embodiments, similar to the above, the tissue thickness compensator  11620  can comprise a plurality of detachable segments  11620   a - 11620   e  which can each be held to support portion  11610  by one or more fasteners  11613 , for example. In the event that the firing member  10052  is stopped intermediate the proximal end  11601  and the distal end  11602  of the staple cartridge  11600 , as illustrated in  FIG. 324 , the fasteners  11613  can assist in holding the unimplanted portion of the tissue thickness compensator  11620  to the support portion  11610  after the anvil  11660  is opened and the support portion  11610  is moved away from the tissue T, as illustrated in  FIG. 325 . In various embodiments, further to the above, the cutting edge  10053  of the firing member  10052  can be configured to incise and/or break the fasteners  11613 . In certain alternative embodiments, referring now to  FIGS. 327 and 328 , a staple-deploying sled, such as sled  11650 , for example, can comprise a knife edge  11653  which can be configured to incise the connectors  11616  of the fasteners  11613  as the sled  11650  traverses the staple cartridge  11600 . In at least one such embodiment, each connector  11616  can comprise a cylindrical member extending between the T-shaped ends  11618  of the fasteners  11613  wherein the knife edge  11653  can comprise a concave profile  11653  which can be configured to receive the cylindrical connector  11616 , for example. 
     As discussed above, a staple cartridge can be loaded into a staple cartridge channel of a surgical stapling instrument. In various circumstances, a surgeon, or other clinician, may insert the staple cartridge into the staple cartridge channel by placing a downward force onto the staple cartridge to lock the staple cartridge in place. In some such circumstances, the clinician may place their thumb, for example, on the top surface of the staple cartridge to apply such a downward force. In various embodiments, the top surface of the staple cartridge may comprise the top surface of a tissue thickness compensator wherein, as described above, the tissue thickness compensator can be compressible and, in certain embodiments, the downward force applied to tissue thickness compensator can cause the tissue thickness compensator to compress to the point in which the clinician&#39;s thumb comes into contact with the tips of the staples stored within the support portion. In various embodiments, a staple cartridge applicator can be utilized to insert a staple cartridge into a staple cartridge channel which can be configured to prevent, or at least limit, the possibility of the clinician touching the staples in the staple cartridge. After the staple cartridge has been suitably positioned within the staple cartridge channel, as described in greater detail below, the applicator can be detached from the staple cartridge. 
     In certain embodiments, referring now to  FIGS. 305 and 306 , a staple cartridge applicator can comprise a rigid cover, such as cover  10080 , for example, which can be attached to a staple cartridge  10000 . Further to the above, the cover  10080  can be configured to prevent, or at least inhibit, a clinician&#39;s thumb, for example, from contacting the tips of the staples  10030  positioned within the staple cartridge  10000  when the staple cartridge  10000  is inserted into a staple cartridge channel. Referring now to  FIGS. 307 and 308 , the cover  10080  can extend over the top surface  10021 , or at least a portion of the top surface  10021 , of the tissue thickness compensator  10020  and can include, one, a bottom surface  10081  which can extend over and/or abut the tissue thickness compensator  10020  and, two, a top surface  10082  which can provide a pushing surface for the clinician to apply a downward force thereto, for example. In use, the clinician can grab a handle portion  10084  of the cover  10080 , align the support portion  10010  of the staple cartridge  10000  with the staple cartridge channel, and at least partially insert the staple cartridge  10000  within the staple cartridge channel. Thereafter, the clinician can completely seat the staple cartridge  10000  in the staple cartridge channel by applying the downward force to the top surface  10082  of the cover  10880  which can, in various embodiments, transmit the downward force directly to the support portion  10010 . In at least one such embodiment, the cover  10080  can comprise proximal supports  10087  which can extend downwardly and contact the deck surface  10011  of the support portion. In certain embodiments, the cover  10080  can further comprise a distal support portion  10083  which can be configured to abut the nose  10003 . When a downward force is applied the cover  10080 , the downward force can be transmitted through the proximal supports  10087  and/or the distal support portion  10083  without transmitting, or at least without substantially transmitting, the downward force to the support portion  10010  through the tissue thickness compensator  10020 . In various circumstances, as a result of the above, the clinician may not directly contact the tissue thickness compensator  10020 . Also as a result of the above, the cover  10080  may not compress, or at least substantially compress, the tissue thickness compensator  10020  as the staple cartridge  10000  is being inserted into the staple cartridge channel. In various embodiments, a cover can comprise any suitable number of supports which are configured to transmit a downward force to the support portion without transmitting, or at least substantially transmitting, the downward force through the tissue thickness compensator. In certain embodiments, the supports can extend around the distal end, the proximal end, and/or the longitudinal sides of the tissue thickness compensator. In some embodiments, the supports can extend through the tissue thickness compensator. In at least one such embodiment, the supports can extend through apertures within the tissue thickness compensator and abut the deck of the support portion. In certain embodiments, at least some of the supports may not be in contact with the deck before the downward force is applied to the cover; however, in various embodiments, the cover can be configured to flex, or move, downwardly until the supports contact the deck of the support portion. At such point, the downward flexure, or movement, of the cover can be impeded, or at least substantially impeded, from flexing further. 
     As described above, the cover  10080  can be attached to the staple cartridge  10000  and can be used to manipulate the position of the staple cartridge  10000 . In various embodiments, the cover  10080  can comprise any suitable number of gripping members which can be configured to releasably hold the cover  10080  to the support portion  10010  of the staple cartridge  10000 , for example. In at least one such embodiment, the cover  10080  can further comprise one or more retention members, such as latch arms  10088  and/or  10089 , for example. In various embodiments, the latch arms  10089  can be configured to extend around the sides of the nose  10003  and engage the bottom surface  10009  ( FIG. 306 ) of the nose  10003 . Similarly, the latch arms  10088  can extend around the sides of lock projections  10008  extending from the support portion  10010  and engage the bottom surfaces of the lock projections  10008 . These latch arms, in various embodiments, can be configured to position the cover  10080  over the zone or region in which the staples are stored within the support portion  10010 . In any event, once the staple cartridge  10000  has been suitably positioned, the cover  10080  can be detached from the staple cartridge  10000 . In at least one embodiment, the clinician can apply an upward lifting force to the handle  10084  in order to detach the distal end of the cover  10080  from the distal end  10002  of the staple cartridge  10000 . In at least one such embodiment, the latch arms  10088  and  10089  can flex outwardly as the handle  10084  is lifted upwardly such that the latch arms  10088  and  10089  can flex around the lock projections  10008  and the nose  10003 , respectively. Thereafter, the proximal end of the cover  10080  can be lifted away from the proximal end  10001  of the staple cartridge and the cover  10080  can be moved away from the staple cartridge  10000 . 
     In certain embodiments, referring now to  FIGS. 309 and 310 , a staple cartridge applicator, such as staple cartridge applicator  10680 , for example, can be configured to position an upper tissue thickness compensator, such as tissue thickness compensator  10690 , for example, relative to an anvil in addition to positioning a staple cartridge, such as staple cartridge  10600 , for example, within a staple cartridge channel. Similar to the above, the applicator  10680  can comprise latch arms  10688  which can be releasably engaged with lock projections  10608  extending from a support portion  10610  of the staple cartridge  10600  such that the applicator  10680  can be maintained in position over a tissue thickness compensator  10620  of the staple cartridge  10600 . In various embodiments, the upper tissue thickness compensator  10690  can be removably attached to the staple cartridge applicator  10680  such that the anvil of a surgical instrument, such as anvil  10060 , for example, can be closed onto the applicator  10680 , engage the tissue thickness compensator  10690 , and detach the tissue thickness compensator  10690  from the applicator  10680 . In various embodiments, the tissue thickness compensator  10690  and/or the anvil  10060  can comprise one or more retention features which can be configured to releasably hold the tissue thickness compensator  10690  to the anvil  10060 . In at least one such embodiment, the tissue thickness compensator  10690  can comprise a longitudinal rail  10695 , for example, extending from the top surface  10691  of the tissue thickness compensator  10690  which can be received within a longitudinal knife slot  10065  defined within the anvil  10060 . In various embodiments, the tissue thickness compensator  10690  and the longitudinal rail  10695  can be comprised of any suitable compressible material, such as those described in the this patent application, for example, wherein the longitudinal rail  10695  can be compressed and/or wedged within the knife slot  10065 , for example. Once the anvil  10060  has been engaged with the tissue thickness compensator  10690 , the anvil  10060  can be returned to an open position and, in such circumstances, the tissue thickness compensator  10690  can detach from the applicator  10680 . Thereafter, the applicator  10680  can be detached from the staple cartridge  10600  such that the anvil  10060  and the staple cartridge  10600  can be positioned relative to the tissue that is to be stapled and/or incised. In use, a staple-deploying sled, such as sled  10050  ( FIG. 236 ), for example, can be advanced distally through the staple cartridge  10600  by a firing member  10052  ( FIG. 236 ), for example, in order to eject the staples from the staple cartridge  10060 , as outlined above. As the staples are deformed, each staple can capture a portion of the tissue thickness compensator  10690  against the top surface of the tissue and a portion of the tissue thickness compensator  10620  against the bottom surface of the tissue. At the same time, the firing member  10052  can advance a knife edge  10053  ( FIG. 236 ) through the tissue thickness compensator  10620  and/or the tissue thickness compensator  10690  wherein, in at least one embodiment, the knife edge  10053  can be advanced through the longitudinal rail  10695  in order to incise the rail  10695  and progressively detach the tissue thickness compensator  10690  from the anvil  10060 . After the staples have been deployed, the anvil  10060  can be re-opened and moved away from the implanted tissue thickness compensator  10690  and, similarly, the support portion  10610  of the staple cartridge  10600  can be moved away from the implanted tissue thickness compensator  10620 . In various embodiments, further to the above, the tissue thickness compensator  10620  and/or the tissue thickness compensator  10690  can comprise a plurality of detachable segments which can be configured to separate from one another in the event that only portions of the tissue thickness compensators  10620  and  10690  are implanted by the staples. 
     In various embodiments, further to the above, the applicator  10680  can comprise one or more retention features which can be configured to releasably hold the tissue thickness compensator  10690  to the applicator  10680 . In at least one such embodiment, referring primarily to  FIG. 310 , the applicator  10680  can comprise a longitudinal retention rail  10685  which can be configured to be received in a longitudinal retention slot  10694  defined in the bottom surface  10692  of the tissue thickness compensator  10690  in a press-fit manner, for example. In various circumstances, the retention rail  10685  and the retention slot  10694  can be configured to retain the tissue thickness compensator  10690  to the applicator  10680  until a sufficient upward lifting force is applied to the tissue thickness compensator  10690  by the anvil  10060 , as described above. In at least one such embodiment, the retention rail  10685  extending from the applicator  10680  can further comprise end stops  10686  positioned at the proximal and distal ends of the retention rail  10685  which can be configured to prevent, or at least limit, relative longitudinal movement between the tissue thickness compensator  10690  and the applicator  10680 . In certain embodiments, referring again to  FIG. 310 , one or more adhesives, such as longitudinal adhesive strips  10693 , for example, can be placed on the contact surface  10691  of the tissue thickness compensator  10690  such that, when the anvil  10060  contacts the tissue thickness compensator  10690 , as described above, the adhesive can releasably attach the tissue thickness compensator  10690  to the anvil  10060 . In various embodiments, one or more adhesives can be utilized in addition to or in lieu of the compressible retention features described above, for example. In certain embodiments, one or more adhesives can be utilized to releasably hold a tissue thickness compensator to a staple cartridge applicator. In at least one embodiment, referring now to  FIG. 310A , the cover  10080 , for example, can include one or more adhesive pads  12185  which can be configured to releasably retain an upper tissue thickness compensator, such as tissue thickness compensator  12190 , for example, to the top surface  10082  of the cover  10080 . In at least one such embodiment, similar to the embodiments described above, an anvil can be closed onto to the tissue thickness compensator  12190  to engage the longitudinal retention rail  12195  of the tissue thickness compensator  12190 . In certain embodiments, a release mechanism can be positioned intermediate the tissue thickness compensator  12190  and the cover  10080  which can be utilized to break the adhesive bonds holding the tissue thickness compensator  12190  to the cover  10080  and detach the tissue thickness compensator  12190  from the cover  10080 . In at least one embodiment, the release mechanism can comprise a pull tab  12196  and a loop  12197  wherein the loop  12197  can comprise first and second ends which are attached to the pull tab  12196 . The loop  12197  can comprise a suture, for example, which can define a perimeter which circumscribes the adhesive pads  12185  such that, when the pull tab  12196  is pulled distally, the suture can slide between the tissue thickness compensator  12190  and the cover  10080  and contact the tissue pads  12185 . In such circumstances, the suture can at least one of separate the adhesive pads  12185  from the tissue thickness compensator  12190 , separate the adhesive pads  12185  from the cover  10080 , and/or sever the adhesive pads  12185 , for example. 
     In various embodiments, referring now to  FIG. 311 , a staple cartridge can comprise a support portion  10710 , for example, which, similar to the above, can comprise a longitudinal knife slot  10715  extending therethrough. In at least one such embodiment, a staple cartridge applicator, such as applicator  10780 , for example, can comprise a longitudinal retention and alignment member  10786  which can extend into the knife slot  10715  in the support portion  10710 . In certain embodiments, the retention member  10786  can be configured to engage the sidewalls of the knife slot  10715  in a press-fit manner, for example, such that the applicator  10780  can be releasably retained to the support portion  10710 . In various embodiments, although not illustrated, a first portion of a tissue thickness compensator can be positioned on a first side of the retention member  10786  and a second portion of the tissue thickness compensator can be positioned on an opposite, or second, side of the retention member  10786 . Similar to the above, the first and second portions of the tissue thickness compensator can be mounted to the support portion  10710  of the staple cartridge via retention members  10013 , for example. Also similar to the above, an upper tissue thickness compensator  10790  can be removably mounted to the applicator  10780  via a longitudinal retention member  10785  extending from the loading surface  10782  of the applicator  10780  wherein the retention member  10785  can be releasably press-fit into a longitudinal slot  10794  defined in the bottom surface  10792  of the tissue thickness compensator  10790 , for example. In various embodiments, also similar to the above, the tissue thickness compensator  10790  can further comprise a longitudinal retention member  10795  extending from the top surface  10791  of the tissue thickness compensator  10790  which can be releasably retained in the longitudinal knife slot  10065  defined in the anvil  10060 , for example. In at least one such embodiment, the longitudinal retention member  10795  can comprise a wedge-shaped cross-section comprising a top portion which is larger than a bottom portion, wherein the bottom portion can attach the retention member  10795  to the tissue thickness compensator  10790 , for example. 
     In various embodiments, referring now to  FIGS. 312 and 313 , a staple cartridge  10800  comprising a support portion  10810  and a tissue thickness compensator  10820  can be loaded into a staple cartridge channel with a staple cartridge applicator  10880 , for example. Similar to the above, the staple cartridge applicator  10880  can also be configured to position an upper tissue thickness compensator  10890 , for example, relative to an anvil, such as anvil  10060 , for example, such that, when the anvil  10060  is closed, the anvil  10060  can contact and engage the tissue thickness compensator  10890 . In at least one embodiment, the tissue thickness compensator  10890  can comprise a plurality of retention legs  10895  extending from the top surface  10891  of the tissue thickness compensator  10890  which can be configured to be engage the anvil  10060  and releasably retain the tissue thickness compensator  10890  to the anvil  10060 . In at least one such embodiment, the legs  10895  can be arranged in a longitudinal row wherein each leg  10895  can comprise at least one foot configured to enter into and engage the knife slot  10065  defined in the anvil  10060 . In certain embodiments, some of the feet of legs  10895  can extend in one direction while other feet can extend in another direction. In at least one embodiment, some of the feet can extend in opposite directions. In any event, once the anvil  10060  has been engaged with the tissue thickness compensator  10890 , referring now to  FIGS. 313 and 314 , the anvil  10060  can be reopened and the clinician can move the staple cartridge applicator  10880  away from the tissue thickness compensators  10820  and  10890 . Thereafter, referring to  FIG. 314A , the upper tissue thickness compensator  10890  can be positioned on a first side of the targeted tissue and the tissue thickness compensator  10820 , which can comprise a lower tissue thickness compensator, can be positioned on a second side of the tissue. After the tissue thickness compensators  10820  and  10890  have been suitably positioned, referring now to  FIG. 314B , a knife edge of a firing member, such as knife edge  10053 , for example, can be advanced through the tissue and the tissue thickness compensators. In various embodiments, referring now to  FIG. 318 , a staple cartridge applicator, such as applicator  12280 , for example, can comprise a tissue thickness compensator  12290  detachably mounted thereto which can be, similar to the above, inserted into a staple cartridge channel, as illustrated in  FIG. 319 , and engaged by the anvil  10060  when the anvil  10060  is moved into a closed position. In at least one such embodiment, the tissue thickness compensator  12290  can comprise a plurality of retention members  12295  extending upwardly from the top surface  12291  of the tissue thickness compensator  12290  wherein each retention member  12295  can comprise a plurality of flexible legs  12296  which can be configured to be inserted into the knife slot  10065  in the anvil  10060 . Referring primarily to  FIGS. 321 and 322 , the flexible legs  12296  of each retention member  12295  can be separated by a gap  12298  such that, as the legs  12296  are inserted into the knife slot  10065 , the legs  12296  can flex inwardly and then resiliently return outwardly once the enlarged feet of the flexible legs  12296  have passed through the knife slot  10065 . In various embodiments, the enlarged feet of the flexible legs  12296  can flex behind opposing retention lips  12297  defined in the anvil  10060  and, as a result of the interaction of the legs  12296  and the lips  12297 , the tissue thickness compensator  12290  can be retained to the anvil  10060 . Thereafter, the staple cartridge applicator  12280  can be moved away from the tissue thickness compensator  12290 , as illustrated in  FIG. 320 . In use, once the tissue thickness compensator  12290  has been implanted against the tissue by staples deployed from staple cartridge  10000 , for example, the anvil  10060  can be re-opened and, as the anvil  10060  is moved away from the implanted tissue thickness compensator  12290 , the legs  12296  of the retention members  12995  can flex inwardly such that they can be pulled out of the knife slot  10065 . 
     In various embodiments, referring now to  FIGS. 315 and 316 , a tissue thickness compensator, such as tissue thickness compensator  11990 , for example, can be loaded longitudinally into an anvil, such as anvil  11960 , for example. More particularly, in at least one embodiment, the tissue thickness compensator  11990  can comprise one or more longitudinal rails  11995  which can be inserted into a distal opening in a knife slot  11965  of the anvil  11960  and then pushed proximally until the tissue thickness compensator  11990  has been properly seated in the anvil  11960 . In at least one such embodiment, each rail  11995  can comprise a longitudinal retention foot  11996  which can be positioned behind a longitudinal retention lip  11997  which at least partially defines the knife slot  11965 , for example. As illustrated in  FIG. 316 , the feet  11996  can extend in opposite directions in order to be positioned behind retention lips  11997  positioned on the opposite sides of the knife slot  11965 . In various embodiments, a longitudinal gap  11998  can be defined between the rails  11995  which can be configured to permit the rails  11995  to flex inwardly toward one another when the tissue thickness compensator  11990  is detached from the anvil  11960 . In certain embodiments, referring now to  FIG. 317 , a tissue thickness compensator, such as tissue thickness compensator  12090 , for example, can comprise one or more lock arms  12098  which can extend around the sides of an anvil, such as anvil  12060 , for example. In use, the lock arms  12098  can engage the anvil  12060  and releasably retain the tissue thickness compensator  12090  to the anvil  12060 . In at least one such embodiment, the anvil  12060  can comprise one or more notches, or lock shoulders,  12097 , for example, which can each be configured to receive a foot extending from a lock arm  12098 . In use, the arms  12098  can flex outwardly and detach from the anvil  12060  when the anvil  12060  is moved away from the tissue thickness compensator  12090  after the tissue thickness compensator  12090  has been at least partially implanted. 
     As described above, a surgical stapling instrument can comprise a staple cartridge channel configured to receive a staple cartridge, an anvil rotatably coupled to the staple cartridge channel, and a firing member comprising a knife edge which is movable relative to the anvil and the staple cartridge channel. In use, a staple cartridge can be positioned within the staple cartridge channel and, after the staple cartridge has been at least partially expended, the staple cartridge can be removed from the staple cartridge channel and replaced with a new staple cartridge. In some such embodiments, the staple cartridge channel, the anvil, and/or the firing member of the surgical stapling instrument may be re-used with the replacement staple cartridge. In certain other embodiments, a staple cartridge may comprise a part of a disposable loading unit assembly which can include a staple cartridge channel, an anvil, and/or a firing member, for example, which can be replaced along with the staple cartridge as part of replacing the disposable loading unit assembly. Certain disposable loading unit assemblies are disclosed in U.S. patent application Ser. No. 12/031,817, entitled END EFFECTOR COUPLING ARRANGEMENTS FOR A SURGICAL CUTTING AND STAPLING INSTRUMENT, which was filed on Feb. 15, 2008, now U.S. Patent Application Publication No. 2009/0206131, the entire disclosure of which is incorporated by reference herein. Referring now to  FIG. 370 , a disposable loading unit, such as disposable loading unit  12500 , for example, can comprise a support portion  12510 , an anvil  12560  rotatably coupled to the support portion  12510 , and an elongate shaft  12570  extending from the support portion  12510 . Similar to the staple cartridges described herein, the support portion  12510  can comprise a plurality of staple cavities  10012  and a staple, such as a staple  10030 , for example, positioned in each staple cavity  10012 , for example. The disposable loading unit  12500  can further comprise a firing member  12552  which can be advanced distally in order to move the anvil  12560  from an open position, as illustrated in  FIG. 370 , to a closed position. In various embodiments, the disposable loading unit  12500  can further comprise a tissue thickness compensator  12520  positioned on and/or attached to the support portion  12510  wherein, when the anvil  12560  is in its closed position, the anvil  12560  can be positioned opposite the tissue thickness compensator  12520  and, in some embodiments, the anvil  12560  can at least partially compress the tissue thickness compensator  12520  when the anvil  12560  is in its closed position. In either event, the firing member  12552  can be advanced further in order to eject the staples from the support portion  12510 . As the staples are ejected, the staples can be deformed by the anvil  12560  and trap at least a portion of the tissue thickness compensator  12520  therein. Thereafter, the firing member  12552  can be retracted proximally, the anvil  12560  can be re-opened, and the support portion  12510  can be moved away from the implanted tissue thickness compensator  12520 . 
     In various embodiments, further to the above, the tissue thickness compensator  12520  can be detachably mounted to the support portion  12510 . In at least one such embodiment, the support portion  12510  can comprise a longitudinal retention rail  12526  mounted to each side thereof wherein each rail  12526  can comprise one or more apertures  12528  which can be configured to receive at least a portion of the tissue thickness compensator  12520  therein. Once the tissue thickness compensator  12520  has been at least partially implanted, the tissue thickness compensator  12520  can pull out of the apertures  12528  as the support portion  12510  is moved away. In various embodiments, referring now to  FIGS. 371-373 , a disposable loading unit  12600  can comprise a support portion  12610 , a tissue thickness compensator  12620  detachably mounted to the support portion  12610 , and one or more retention rails  12626  which can be configured to extend under the tissue thickness compensator  12620  and mount the tissue thickness compensator  12620  to the support portion  12610 . Each retention rail  12626  can comprise a plurality of retention hooks  12628 , for example, which can be engaged to the support portion  12610  via retention slots  12614 , for example, defined in the support portion  12610 . In use, in at least one such embodiment, the tissue thickness compensator  12620  can be configured to detach from the retention rails  12626  after the tissue thickness compensator  12620  has been at least partially implanted and the support portion  12610  is moved away from the tissue thickness compensator  12620 . In various embodiments, referring now to  FIGS. 374-376 , a disposable loading unit  12700  can comprise one or more retention rails  12726  which can each comprise a bottom bar  12725  which can extend under the tissue thickness compensator  12720  and a top bar  12727  which can extend over the top surface  12621  of the tissue thickness compensator  12620 . In certain embodiments, the tissue thickness compensator  12620  can be at least partially compressed between the top bars  12727  and the bottom bars  12725  such that the retention rails  12726  can releasably hold the tissue thickness compensator  12620  relative to the support portion  12610 . In at least one such embodiment, each retention rail  12726  can comprise one or more retention hooks  12728  which can be engaged with the support portion  12610  to retain the retention rails  12726  to the support portion  12610 . 
     In various embodiments, referring now to  FIGS. 377 and 378 , a disposable loading unit  12800  can comprise a retention member  12822  which can be configured to mount a tissue thickness compensator  12620  to the support portion  12610 . In at least one such embodiment, the retention member  12822  can comprise a sheet of material positioned against the deck surface  12611  of the support portion wherein the tissue thickness compensator  12620  can be attached to the sheet of material by at least one adhesive, for example. The retention member  12822  can further comprise a longitudinal retention rail  12825  configured to extend downwardly into a knife slot  12615  defined in the support portion  12610 . In at least one such embodiment, the retention rail  12825  can be sized and configured such that it is compressed between the sidewalls of the knife slot  12615 . In use, the firing member  12552  can comprise a knife edge which can pass through the knife slot  12615  as the firing member  12552  is advanced distally and transect the tissue thickness compensator  12620  and the retention rail  12825  longitudinally. Also, in use, the staples ejected from the support portion  12610  can penetrate the retention member  12822 , the tissue thickness compensator  12820 , and the tissue positioned between the tissue thickness compensator  12820  and the anvil  12560 . In various embodiments, the retention member  12822  can be comprised of a biocompatible and/or bioabsorbable material. In certain embodiments, the retention member  12822  can be comprised of a sufficiently compressible material to comprise a tissue thickness compensator underlying the tissue thickness compensator  12620 . In various embodiments, referring now to  FIGS. 379-381 , a disposable loading unit  12900  can comprise a loading assembly including a bottom portion  12922  which can be removably attached to the support portion  12610 , a top portion  12990  which can be removably attached to the anvil  12560 , and a flexible joint  12991  connecting the bottom portion  12922  and the top portion  12990 . Similar to the above, a longitudinal retention rail  12825  can extend downwardly from the bottom portion  12922  and into the knife slot  12615  defined in the support portion  12610  such that the bottom portion  12922  can be releasably retained to the support portion  12610 . Similarly, a longitudinal retention rail  12995  can extend upwardly from the top portion  12990  into a knife slot defined in the anvil  12560  such that the top portion  12990  can be releasably retained to the anvil  12560 . As illustrated in  FIGS. 380 and 381 , a tissue thickness compensator  12620  can be mounted to the bottom portion  12922  of the loading assembly wherein, in order to position the tissue thickness compensator  12620  relative to the support portion  12610 , a clinician could flex the top portion  12990  and the bottom portion  12922  toward one another, position the loading assembly between the anvil  12560  and the support portion  12610 , and release the flexed loading assembly such that it can resiliently expand and bias the top portion  12990  against the anvil  12560  and the bottom portion  12922  against the support portion  12610 . In at least one embodiment, referring now to  FIGS. 382-384 , the loading assembly can further comprise one or more latch hooks, such as latch hooks  12994 , for example, extending therefrom which can be configured to releasably connect the top portion  12990  to the anvil  12560  and/or releasably connect the bottom portion  12922  to the support portion  12610 . 
     In various embodiments, referring now to  FIG. 385 , a disposable loading unit  15900 , for example, can comprise an anvil  15960  and a staple cartridge channel  15970  wherein the staple cartridge channel  15970  can rotate relative to the anvil  15960 . In at least one such embodiment, the anvil  15960  may not be able to rotate. In certain embodiments, tissue can be positioned between the anvil  15960  and the staple cartridge channel  15970  and, thereafter, the staple cartridge channel  15970  can be rotated toward the tissue to clamp the tissue against the anvil. In at least one such embodiment, the disposable loading unit  15900  can further comprise a tissue thickness compensator  15920  which can be configured to contact the tissue. 
     As discussed above and referring to  FIG. 332 , a staple cartridge, such as staple cartridge  10000 , for example, can comprise a support portion  10010  and a tissue thickness compensator  10020  wherein a plurality of staples  10030  can be at least partially stored in the support portion  10010  and can extend into the tissue thickness compensator  10020  when the staples  10030  are in their unfired position. In various embodiments, the tips of the staples  10030  do not protrude from the tissue thickness compensator  10020  when the staples  10030  are in their unfired positions. As the staples  10030  are moved from their unfired positions to their fired positions by the staple drivers  10040 , as discussed above, the tips of the staples  10030  can penetrate through the tissue thickness compensator  10020  and/or penetrate through the upper layer, or skin,  10022 . In certain alternative embodiments, the tips of the staples  10030  can protrude through the top surface of the tissue thickness compensator  10020  and/or skin  10022  when the staples  10030  are in their unfired position. In either event, the staples  10030 , as they extend upwardly out of the support portion  10010  prior to being deployed, may tilt and/or deflect relative to the support portion, as also discussed above. In various embodiments, referring now to  FIG. 329 , a staple cartridge, such as staple cartridge  13000 , for example, can comprise a plurality of guide members, or retainers, which can be configured to limit relative movement between the support portion  13010  of the staple cartridge  13000  and the tips of the staples positioned therein. Referring primarily to  FIG. 330 , the staple cartridge  13000  can comprise a tissue thickness compensator  13020  mounted to a support portion  13010  and, in addition, a plurality of pledgets  13022  attached to the top surface  13021  of the tissue thickness compensator  13020 . In various embodiments, each pledget  13022  can comprise a plurality of apertures  13029  defined therein which can be configured to slidably receive and/or guide the legs  13022  of a staple  13030  therein. In addition to or in lieu of the apertures, a pledget can comprise any suitable opening such as a slot, guide, and/or groove, for example, which can be configured to slidably receive and/or guide the legs  13022 . In certain embodiments, as illustrated in  FIG. 330 , the tips of the staple legs  13032  can be positioned within the apertures  13029  when the staples  13030  are in their unfired positions. In at least one such embodiment, the tips of the staple legs  13032  can protrude above the pledgets  13022  when the staples are in their unfired position. In certain other embodiments, the tips of the staple legs  13032  may be positioned just below the pledgets  13022  when the staples  13030  are in their unfired positions such that, when the staples  13030  are moved upwardly through the tissue thickness compensator  13020 , the staple legs  13032  can enter into the apertures  13029  of the pledgets  13022  and slide therethrough. In any event, when the legs  13032  of the staples  13030  are positioned within the pledgets, the lateral and/or longitudinal movement of the staple legs  13032  can be limited without preventing the upward movement of the staple legs  13032  when the staples  13030  are deployed. When the staples  13030  are deployed, referring now to  FIG. 331 , the staple legs  13032  can slide upwardly through the pledgets  13022  to penetrate the tissue T, contact an anvil positioned opposite the staple cartridge  13030 , and deform downwardly to capture the tissue T and the tissue thickness compensator  13030  therein. 
     In various embodiments, further to the above, the pledgets  13022  can be attached to the tissue thickness compensator  13020  utilizing at least one biocompatible and/or bioabsorbable adhesive, for example. In certain embodiments, the pledgets  13022 , and/or a retention member extending from each pledget, can be at least partially embedded within the tissue thickness compensator  13020 . In at least one such embodiment, the tissue thickness compensator  13020  can comprise pockets defined therein which are configured to at least partially receive a pledget  13022 . In certain embodiments, the tissue thickness compensator  13020  can be integrally molded, or formed around, the pledgets  13022  during a molding manufacturing process. In various embodiments, the pledgets  13022  may comprise discrete retainers that can move independently of one another. In at least one embodiment, referring primarily to  FIG. 330 , each pledget  13022  can comprise interlocking and/or keyed features which can be configured to permit and, to a certain extent, limit relative lateral and longitudinal movement between the pledgets  13022 . In at least one such embodiment, each pledget  13022  can comprise a projection  13026  and one or more recesses  13027 , for example, wherein the projection  13026  of a first pledget  13022  can be positioned within and/or aligned with respect to the recesses of  13027  of adjacent second and third pledgets  13022 . In various embodiments, gaps can be present between adjacent pledgets  13022  which can permit the pledgets  13022  to move or slide relative to one another until they contact an adjacent pledget  13022 . In certain embodiments, the pledgets  13022  can be loosely interconnected. In various embodiments, the pledgets  13022  can be detachably connected to one another. In at least one such embodiment, the pledgets  13022  can be manufactured as a sheet of interconnected pledgets wherein, when a sufficient force is applied to the sheet, one or more of the pledgets  13022  can break away from the others. In certain embodiments, referring again to  FIG. 329 , a first sheet  13024  of pledgets  13022  can be positioned on a first side of a longitudinal slot  13025  and a second sheet  13024  of pledgets  13022  can be positioned on a second side of slot  13025 . In at least one embodiment, further to the above, the longitudinal slot  13025  extending through the tissue thickness compensator  13020  can be configured to facilitate the passage of a knife edge of a firing member through the tissue thickness compensator  13020  and, as the firing member passes thereby, the firing member can apply a compressive force to the sheets  13024  and separate or singulate at least some of the pledgets  13022 . 
     In various embodiments, the pledgets  13022  can be comprised of a biocompatible and/or bioabsorbable plastic, for example. In certain embodiments, the pledgets  13022  can be comprised of a solid material, a semi-solid material, and/or a flexible material, for example. In certain embodiments, the pledgets  13022  can be embedded within a tissue thickness compensator such that the pledgets  13022  move with the tissue thickness compensator. In at least one such embodiment, the pledgets  13022  can be sufficiently flexible such that they can flex with the top surface of the tissue thickness compensator. In certain embodiments, the pledgets  13022  can be configured to remain embedded in the tissue thickness compensator while, in certain other embodiments, the pledgets  13022  can be configured to pop out of, or detach from, the tissue thickness compensator. In various embodiments, the pledges  13022  can comprise a top surface which is flush with the top surface of the tissue thickness compensator. In certain embodiments, the top surfaces of the pledgets  13022  can be positioned above and/or below the top surface of the tissue thickness compensator. In various embodiments, the top surfaces of the pledgets  13022  can be disposed such that they are visible when viewing the top surface of the tissue thickness compensator while, in other embodiments, the top surfaces of the pledgets  13022  can be positioned below a layer of the tissue thickness compensator, for example. In certain embodiments, guide features can be molded into the top surface of a tissue thickness compensator, for example. In at least one such embodiment, the tissue thickness compensator may not comprise a composite material and may comprise a unitary piece of material, for example. 
     In various embodiments, referring now to  FIG. 338 , a staple cartridge can comprise a tissue thickness compensator  13620  and a skin, or top layer,  13621 , for example. In at least one such embodiment, one or more pledgets, or retainers,  13622 , for example, can be embedded in the skin  13621 . In certain embodiments, each retainer  13622  can comprise one or more apertures  13629  defined therein which can be configured to receive the staple legs  13032  of staples  13030  therein when the staples  13030  are in their unfired position, as illustrated in  FIG. 338 . In use, further to the above, the staple legs  10032  can slide through the apertures  13629  when the staples  13030  are moved from their unfired position to their fired position until the bases  13031  of the staples  13030  contact the tissue thickness compensator  13620  and compress at least a portion of the tissue thickness compensator  13620  against the bottom surfaces of the pledgets  13622 , for example. In various embodiments, referring now to  FIG. 333 , a staple cartridge can comprise a tissue thickness compensator  13120  and a skin, or top layer,  13122 , for example. In at least one such embodiment, the tissue thickness compensator  13120  can comprise conical bumps, projections, and/or protrusions  13128 , for example, which can extend upwardly from the top surface  13121  of the tissue thickness compensator  13120 . The projections  13128  can be configured to receive and envelop the tips of the staple legs  13032  of the staples  13030  when the staples  13030  are in their unfired position, as illustrated in  FIG. 333 . The top layer  13122  can also comprise conical bumps, projections, and/or protrusions  13129  which can be aligned, or at least substantially aligned, with the projections  13128 . In use, the staple legs  10032  can penetrate the projections  13128  and  13129  and emerge from the tissue thickness compensator  13120 . In various embodiments, referring now to  FIG. 337 , a staple cartridge can comprise a tissue thickness compensator  13520  and a skin, or top layer,  13522 , for example. In at least one such embodiment, the skin  13522  can comprise conical bumps, projections, and/or protrusions  13529 , for example, which can extend upwardly from the top surface  13521  of the tissue thickness compensator  13520 . Similar to the above, the projections  13529  can be configured to receive and envelop the tips of the staple legs  13032  of the staples  13030  when the staples  13030  are in their unfired position, as illustrated in  FIG. 337 . In use, the staple legs  10032  can penetrate the projections  13529  and emerge from the skin  13522 . 
     In various embodiments, referring now to  FIG. 334 , a staple cartridge can comprise a tissue thickness compensator  13220  and a skin, or top layer,  13222 , for example. In at least one such embodiment, the tissue thickness compensator  13220  can comprise conical dimples and/or recesses  13128 , for example, which can extend downwardly into the top surface  13221  of the tissue thickness compensator  13220 . In various embodiments, the tips of the staple legs  13032  can extend through the recesses  13128  when the staples  13030  are in their unfired position, as illustrated in  FIG. 334 . In at least one embodiment, the top layer  13222  can also comprise conical dimples and/or recesses  13229  which can be aligned, or at least substantially aligned, with the recesses  13228 . In various embodiments, referring now to  FIG. 335 , a staple cartridge can comprise a tissue thickness compensator  13320  and a skin, or top layer,  13322 , for example. In at least one such embodiment, the skin  13320  can comprise thick portions  13329  which can extend downwardly into the top surface  13321  of the tissue thickness compensator  13320 . In various circumstances, the thick portions  13329  can be configured to receive at least a portion of the staple legs  13032  of the staples  13030  therein when the staples  13030  are in their unfired position, as illustrated in  FIG. 335 . In such embodiments, the thick portions  13329  can hold the staple legs  13032  in position such that the legs  13032  are aligned, or at least substantially aligned, with the staple-forming pockets of an anvil positioned opposite the tissue thickness compensator  13320 . In various embodiments, referring now to  FIG. 336 , a staple cartridge can comprise a tissue thickness compensator  13420  and a skin, or top layer,  13422 , for example. In at least one such embodiment, the skin  13422  can comprise thick portions  13429  which can extend upwardly from the top surface  13421  of the tissue thickness compensator  13420 . In various circumstances, the thick portions  13429  can be configured to receive at least a portion of the staple legs  13032  of the staples  13030  therein when the staples  13030  are in their unfired position, as illustrated in  FIG. 336 . In such embodiments, the thick portions  13429  can hold the staple legs  13032  in position such that the legs  13032  are aligned, or at least substantially aligned, with the staple-forming pockets of an anvil positioned opposite the tissue thickness compensator  13420 . 
     In various embodiments, referring now to  FIGS. 339 and 340 , a staple cartridge can comprise a tissue thickness compensator  13720  and a skin, or top layer,  13721 , for example. In at least one such embodiment, the tissue thickness compensator  13720  can comprise pyramidal and/or stepped bumps, projections, and/or protrusions  13728 , for example, which can extend upwardly from the top surface  13721  of the tissue thickness compensator  13720 . The projections  13728  can be configured to receive and envelop the tips of the staple legs  13032  of the staples  13030  when the staples  13030  are in their unfired position, as illustrated in  FIG. 340 . Similarly, the top layer  13721  can comprise pyramidal and/or stepped bumps, projections, and/or protrusions  13729  which can be aligned, or at least substantially aligned, with the projections  13728 . In various embodiments, the skin  13721  can further comprise one or more teeth  13727  extending upwardly from the projections  13729  which can be configured to engage tissue positioned against the top layer  13721  and prevent, or at least limit, relative lateral and/or longitudinal movement between the tissue, the top layer  13721 , and/or the tips of the staple legs  13032 . In use, the staple legs  13032  can penetrate the projections  13728  and  13729  and emerge from the tissue thickness compensator  13720  when the staples  13030  are moved from their unfired positions to their fired positions. In various embodiments, referring now to  FIGS. 341 and 342 , a staple cartridge can comprise a tissue thickness compensator  13820  and a skin, or top layer,  13821 , for example. In at least one such embodiment, the tissue thickness compensator  13820  can comprise pyramidal and/or stepped bumps, projections, and/or protrusions  13828 , for example, which can extend upwardly from the top surface  13821  of the tissue thickness compensator  13820 . The projections  13828  can be configured to receive and envelop the tips of the staple legs  13032  of the staples  13030  when the staples  13030  are in their unfired position, as illustrated in  FIG. 342 . Similarly, the top layer  13821  can comprise pyramidal and/or stepped bumps, projections, and/or protrusions  13829  which can be aligned, or at least substantially aligned, with the projections  13828 . In various embodiments, the top layer  13821  can further comprise one or more teeth  13827  extending downwardly into the tissue thickness compensator  13820  which can be configured to prevent, or at least limit, relative lateral and/or longitudinal movement between the top layer  13821  and the tissue thickness compensator  13820 , for example. In use, the staple legs  10032  can penetrate the projections  13828  and  13829  and emerge from the tissue thickness compensator  13820  when the staples  13030  are moved from their unfired positions and their fired positions. 
     In various embodiments, referring now to  FIG. 343 , a staple cartridge can comprise a tissue thickness compensator, such as tissue thickness compensator  13920 , for example, which can include ridges  13923  and valleys  13924  defined therein wherein, in at least one embodiment, the valleys  13924  can be defined between the ridges  13923 . In various embodiments, each ridge  13923  can comprise the same height, substantially the same height, or different heights. Similarly, each valley  13924  can comprise the same depth, substantially the same depth, or different depths. In various embodiments, a plurality of staples  13030  can be at least partially stored within the tissue thickness compensator  13920  such that the tips of the staples  13030  can be positioned within the ridges  13923 . In at least one such embodiment, the staple legs  13032  of the staples  13030  may not protrude from the tissue thickness compensator  13920  and/or a skin, or top layer,  13921  attached to the tissue thickness compensator  13920 , for example, when the staples  13030  are stored in their unfired position. In various embodiments, the ridges  13923  and/or the valleys  13924  can extend laterally across the staple cartridge. In at least one such embodiment, the staple cartridge can comprise a longitudinal knife slot wherein the ridges  13923  and the valleys  13924  can extend in a direction which is transverse and/or perpendicular to the knife slot. In various circumstances, the ridges  13923  can be configured to hold the tips of the staple legs  13032  in position until the staples  13030  are moved from their unfired position into their fired position. In various embodiments, referring now to  FIG. 344 , a tissue thickness compensator, and/or a skin covering a tissue thickness compensator, can comprise longitudinal ridges and/or valleys. In at least one such embodiment, a tissue thickness compensator can comprise a top surface defined by ridges  14023  and valleys  14024 , wherein the valleys  14024  can be defined between the ridges  14023 , for example. In various embodiments, the tissue thickness compensator can comprise a skin  14021  which can include a plurality of apertures  14029  defined therein which can each be configured to receive a staple leg  13032 . In certain embodiments, the apertures  14029  can be defined in the ridges  14023  wherein the tips of the staple legs  13032  may be positioned below the peaks  14028  of the ridges  14029 , positioned flush with the peaks  14028 , and/or positioned above the peaks  14028 . In certain embodiments, in addition to or in lieu of the above, the apertures  14029  can be defined in the valleys  14024 , for example. In certain embodiments, each aperture can be surrounded, or at least partially surrounded, by an embossment, for example, which can strengthen the skin and/or tissue thickness compensator surrounding the apertures. In any event, further to the above, the skin  14021  can be attached to a tissue thickness compensator in any suitable manner, including using at least one adhesive, for example. 
     As described above and referring again to  FIG. 233 , a surgical stapling instrument can comprise an anvil, such as anvil  10060 , for example, which can be moved between an open position and a closed position in order to compress tissue T against the tissue thickness compensator  10020  of a staple cartridge  10000 , for example. In various circumstances, the anvil  10060  can be rotated toward the staple cartridge  10000  until its downward movement is stopped by some portion of the staple cartridge  10000  and/or some portion of the channel in which the staple cartridge  10000  is positioned. In at least one such circumstance, the anvil  10060  can be rotated downwardly until its downward movement is resisted by the nose  10003  of the staple cartridge  10000  and/or the tissue T positioned intermediate the nose  10003  and the staple cartridge  10000 . In some circumstances, the anvil  10060  may sufficiently compress the tissue thickness compensator  10020  to permit the tissue T to contact the tips of the staples  10030 . In certain circumstances, depending on the thickness of the tissue T, the anvil  10060  may sufficiently compress the tissue thickness compensator  10020  such that the anvil  10060  comes into contact with the staples  10030  by the time the anvil  10060  has reached its fully closed position. Stated another way, in such circumstances, the anvil  10060  may deform the staples  10030  prior to the firing member  10052  being advanced into the staple cartridge  10000  to fire the staples  10030 . Such circumstances may be acceptable in certain embodiments; however, referring now to  FIGS. 358 and 359 , other embodiments are envisioned in which a distal gap-setting element, such as element  10059 , for example, can be utilized to limit the distance in which the anvil  10060  can be closed prior to the firing bar  10052  being advanced into the staple cartridge  10000 . In various embodiments, the element  10059  can extend upwardly from the top surface  10021  of the tissue thickness compensator  10020  such that the downward movement of the anvil  10060  can be arrested as the tissue T is compressed against the element  10059  and a resistive force is generated therebetween. In use, as described above, the firing member  10052  can be advanced distally into the staple cartridge  10000  toward the distal end  10002  of the staple cartridge  10000  in order to eject the staples  10030  from the support portion  10010 . Simultaneously, the firing member  10052  can engage the anvil  10060  and position the anvil  10060  a desired distance from the deck surface  10011  ( FIG. 218 ) of the support portion  10010  over the staples  10030  being formed. In this way, the firing member  10052  can control the distance, or gap, between the tissue-contacting surface of the anvil  10060  and the deck surface  10011  at a particular location, wherein this particular location can be advanced distally as the firing member  10052  is advanced distally. In various circumstances, this gap distance may be shorter than the gap between the anvil  10060  and the deck surface  10011  being controlled or dictated by the distal gap-setting element  10059  at the distal end of the tissue thickness compensator  10020 . In various embodiments, referring now to  FIG. 359 , the knife edge  10053  of the firing member  10052  can be configured to transect the distal gap-setting element  10059  when the firing member  10052  reaches the distal end of the tissue thickness compensator  10020  such that, after the element  10059  has been transected, the firing member  10052  can pull the anvil  10060  downwardly toward the support portion  10010  and close the gap to the desired gap height when firing the staples  10030  at the distal end of the staple cartridge  10000 . In certain alternative embodiments, a distal gap-setting element can be configured to collapse as the firing member approaches the distal end of the staple cartridge. In at least one such embodiment, the distal gap-setting element can comprise a column which can provide resistance to the anvil as described above and then suddenly buckle once the buckling strength of the gap-setting element has been reached when the firing member approaches the distal end of the staple cartridge. In at least one embodiment, this buckling force can be approximately 10 lbf, for example. In certain embodiments, a gap setting element can be configured to drop downwardly into the deck of the support portion when a force exceeding a predetermined amount is applied to the gap setting element, for example. In certain other embodiments, the distal gap can be controlled by the nose of the staple cartridge. In at least one such embodiment, the downward movement of the anvil  10060  can be limited by the nose until the firing member has reached the distal end of the cartridge wherein, at such point, the compressive force applied to the nose can cause the nose to collapse. In certain embodiments, the nose can comprise a cavity defined by cavity walls which can allow the cavity to collapse once the compressive force applied thereto has exceed a predetermined force. In at least one such embodiment, the cavity can be defined by collapsible walls. 
     In various embodiments, as described above, an anvil, such as anvil  10060 , for example, can be moved between an open position and a closed position in order to compress a tissue thickness compensator between the anvil and the support portion of a staple cartridge. In certain circumstances, referring now to  FIGS. 360 and 361 , the tissue thickness compensator of a staple cartridge, such as tissue thickness compensator  14120  of staple cartridge  14100 , for example, may expand laterally and/or longitudinally when the tissue thickness compensator  14120  is compressed against a support portion  14110  of the staple cartridge  14100 . In certain embodiments, the ends and/or sides of the tissue thickness compensator  14120  may not be constrained by the support portion  14110  and/or the anvil  10060  and, as a result, the tissue thickness compensator  14120  can expand in those directions without generating a compressive pressure, or at least an undesirable compressive pressure, within the tissue thickness compensator  14120 . In such embodiments, a firing member, such as firing member  10052  ( FIG. 236 ), for example, passing through the tissue thickness compensator  14120  may not be unduly impeded by an undesirable compressive pressure within the tissue thickness compensator  14120 , for example. In certain other embodiments, referring again to  FIG. 360 , the distal end  14125  of the tissue thickness compensator  14120  may be constrained by the nose  14103  of the staple cartridge  14100 , for example. In this particular embodiment, similar to the above, the distal end  14125  of the tissue thickness compensator  14120  may be constrained by the nose  14103  in order to reduce the possibility of the tissue thickness compensator  14120  from becoming prematurely detached from the support portion  14110 . In any event, as a result of the above, a large internal pressure can be generated within the distal end  14125  which can impede the advancement of the firing member  10052 , especially when the firing member  10052  reaches the distal end  14125 . More particularly, in certain circumstances, the firing member  10052  can push, plow, and/or displace the tissue thickness compensator  14120  distally as it transects the tissue thickness compensator  14120  and, as a result, an even larger internal pressure can be created within the distal end  14125  of the tissue thickness compensator  14120 . In order to at least partially dissipate this pressure within the tissue thickness compensator  14120 , the nose  14103  can be comprised of a flexible material which can allow the nose  14103  to flex distally, for example, and create additional space for the tissue thickness compensator  14120 . In certain embodiments, referring now to  FIGS. 362 and 363 , the nose of a staple cartridge can comprise a portion which can slide distally. More particularly, the nose  14203  of the staple cartridge  14200  can comprise a slidable portion  14204  which can be slidably connected to the nose  14203  such that, when the anvil  10060  is closed and/or the firing member  10052  is advanced into the distal end of the staple cartridge  14200 , the slidable portion  14204  can slide distally and create additional room for the tissue thickness compensator  14200  and at least partially alleviate the internal pressure therein. In at least one embodiment, one of the nose  14203  and the slidable portion  14204  can comprise one or more rails and the other of the nose  14203  and the slidable portion  14204  can comprise one or more channels configured to slidably receive the rails therein. In at least one such embodiment, the channels and rails can be configured to co-operatively limit the movement of the slidable portion  14204  to a longitudinal distal path, for example. 
     In various circumstances, further to the above, certain staples, such as the distal-most staples within a staple cartridge, for example, can capture a larger portion of a tissue thickness compensator than the proximal staples within the staple cartridge. In such circumstances, as a result, a large clamping pressure can be applied to the tissue captured within the distal staples as compared to the proximal staples. These circumstances can arise when at least a portion of the tissue thickness compensator is shifted to and/or gathered at the distal end of the staple cartridge during use, as described above, eventhough the tissue thickness compensator may be comprised of a substantially homogenous material having a substantially constant thickness. In various circumstances, it may be desirable for certain staples to apply a higher clamping pressure to the tissue than other staples wherein, in various embodiments, a support portion and/or a tissue thickness compensator can be constructed and arranged to control which staples may apply the higher clamping pressure to the tissue and which staples may apply a lower clamping pressure to the tissue. Referring now to  FIG. 364 , a staple cartridge  14300  can comprise a support portion  14310  and, in addition, a tissue thickness compensator  14320  positioned on the deck surface  14311  of the support portion  14310 . As compared to other embodiments disclosed in this application which comprise a support portion  14310  having a flat, or at least substantially flat, deck surface, the deck surface  14311  can be inclined and/or declined between the distal end  14305  and the proximal end  14306  of the support portion  14310 . In at least one embodiment, the deck surface  14311  of the support portion  14310  can comprise a deck height at its distal end  14305  which is shorter than the deck height at its proximal end  14306 . In at least one such embodiment, the staples  10030  at the distal end of the staple cartridge  14300  can extend above the deck surface  14311  a larger distance than the staples  10030  at the proximal end. In various alternative embodiments, the deck surface of a support portion can comprise a height at its distal end which is taller than its height at its proximal end. Referring again to  FIG. 364 , the tissue thickness compensator  14320  may comprise a thickness which is different along the longitudinal length thereof. In various embodiments, the tissue thickness compensator  14320  can comprise a thickness at its distal end  14325  which is thicker than its proximal end  14326 , for example. In at least one such embodiment, the tissue thickness compensator  14322  can comprise a bottom surface  14322  which can be inclined or declined to match, or at least substantially match, the inclined or declined deck surface  14311  of the support portion  14310 . As a result, the top, or tissue-contacting, surface  14321  of the tissue thickness compensator  14320  can comprise a flat, or at least substantially flat, surface upon which the tissue T can be positioned. In any event, as the tissue thickness compensator  14320  is thicker at its distal end  14325 , the distal staples  10030  can capture a larger portion of the tissue thickness compensator  14320  therein than the proximal staples  10030  and, as a result, the distal staples  10030  can apply a larger compressive force to the tissue T, especially when the gap distance between the anvil  10060  and the deck surface  14311  is constant, or at least substantially constant, at the proximal and distal ends of the staple cartridge. In certain circumstances, however, the anvil  10060  may not reach a fully closed position and, as a result, the gap distance between the anvil  10060  and the deck surface  14311  may be larger at the distal end of the staple cartridge  14300  than the proximal end. In various circumstances, the distal staples  10030  may not be fully formed and, as a result, the distal staples  10030  may not apply the desired clamping pressure to the tissue T. In the embodiments where the tissue thickness compensator is thicker at the distal end of the staple cartridge, the tissue thickness compensator may compensate for the underforming of the staples and apply a sufficient pressure to the tissue T. 
     In various embodiments, referring now to  FIG. 365 , a staple cartridge, such as staple cartridge  14400 , for example, can comprise a support portion  14410  and, in addition, a tissue thickness compensator  14420  positioned on the deck surface  14411  of the support portion  14410 . Similar to the above, the deck surface  14411  can be inclined and/or declined such that, in at least one embodiment, the distal end  14405  of the support portion  14410  can have a deck height which is shorter than the deck height at the proximal end  14406 , for example. In certain embodiments, the tissue thickness compensator  14420  can comprise a constant, or at least substantially constant, thickness along the length thereof and, as a result, the top, or tissue-contacting, surface  14421  of the tissue thickness compensator  14420  may parallel, or at least substantially parallel, the contour of the deck surface  14411 . In various embodiments, the staples  10030  of the staple cartridge  14400  can be completely embedded within the tissue thickness compensator  14420  and the support portion  14410  when the staples  10030  are in their unfired position. In certain embodiments, the staples  10030  positioned at the proximal end of the staple cartridge  14400  may be completely embedded within the tissue thickness compensator  14420  and the support portion  14410  when the staples  10030  are in their unfired position whereas, due to the declined slope of the deck  14411  and top surface  14421 , the tips of certain staples  10030 , including the staples  10030  positioned at the distal end of the staple cartridge  14400 , can protrude through the top surface  14421  of the tissue thickness compensator  14420  when the staples  10030  are in their unfired position. 
     In various embodiments, as described above, a tissue thickness compensator can be comprised of a single material wherein the entirety of the tissue thickness compensator can have the same, or at least substantially the same, material properties, such as density, stiffness, spring rate, durometer, and/or elasticity, for example, throughout. In various other embodiments, referring now to  FIG. 368 , a tissue thickness compensator, such as tissue thickness compensator  14520 , for example, can comprise a plurality of materials or layers of materials. In at least one embodiment, the tissue thickness compensator  14520  can comprise a first, or central, layer  14520   a , second, or intermediate, layers  14520   b  attached to the first layer  14520   a  on opposite sides thereof, and a third, or outer layer  14520   c  attached to each of the second layers  14520   b . In certain embodiments, the intermediate layers  14520   b  can be attached to the central layer  14520   a  utilizing at least one adhesive and, similarly, the outer layers  14520   c  can be attached the second layers  14520  utilizing at least one adhesive. In addition to or in lieu of an adhesive, the layers  14520   a - 14520   c  can be held together by one or more interlocking features and/or fasteners, for example. In any event, the inner layer  14520   a  can be comprised of a first material having a first set of material properties, the intermediate layers  14520   b  can be comprised of a second material having a second set of material properties, and the outer layers  14520   c  can be comprised of a third material having a third set of material properties, for example. These sets of material properties can include density, stiffness, spring rate, durometer, and/or elasticity, for example. In certain embodiments, a staple cartridge can comprise six rows of staples  10030 , for example, wherein a row of staples  10030  can be at least partially positioned in each of the outer layers  14520   c  and each of the inner layers  14520   b , for example, and wherein two rows of staples  10030  can be at least partially positioned with the inner layer  14520   a . In use, similar to the above, the staples  10030  can be ejected from the staple cartridge such that the staple legs  10032  of the staples  10030  penetrate the top surface  14521  of the tissue thickness compensator  14520 , penetrate tissue positioned against the top surface  14521  by an anvil, and then contact the anvil such that the legs  10032  are deformed to capture the tissue thickness compensator  14520  and the tissue within the staples  10030 . Also similar to the above, the tissue thickness compensator  14520  can be transected by a firing member as the firing member is advanced through the staple cartridge. In at least one such embodiment, the firing member can transect the inner layer  14520   a , and the tissue, along a path defined by axis  14529 , for example. 
     In various embodiments, further to the above, the rows of staples  10030  positioned within the inner layer  14520   a  can comprise the staple rows which are closest to the edges of the transected tissue. Correspondingly, the rows of staples  10030  positioned within the outer layers  14520   c  can comprise the staple rows which are furthest away from the edges of the transected tissue. In certain embodiments, the first material comprising the inner layer  14520   a  may comprise a density which is higher than the density of the second material comprising the intermediate layers  14520   b  and, similarly, the density of the second material may be higher than the density of the third material comprising the outer layers  14520   c , for example. In various circumstances, as a result, larger compressive forces can be created within the staples  10030  positioned within the inner layer  14520   a  as compared to the compressive forces generated within the staples  10030  positioned within the intermediate layers  14520   b  and the outer layers  14520   c . Similarly, larger compressive forces can be created within the staples  10030  positioned within the intermediate layers  14520   b  as compared to compressive forces created within the staples  10030  positioned within the outer layers  14520   c , for example. In various alternative embodiments, the first material comprising the inner layer  14520   a  may comprise a density which is lower than the density of the second material comprising the intermediate layers  14520   b  and, similarly, the density of the second material may be lower than the density of the third material comprising the outer layers  14520   c , for example. In various circumstances, as a result, larger compressive forces can be created within the staples  10030  positioned within the outer layers  14520   c  as compared to the compressive forces created within the staples  10030  positioned within the intermediate layers  14520   b  and the inner layer  14520   a . Similarly, larger compressive forces can be created within the staples  10030  positioned within the intermediate layers  14520   b  as compared to the compressive forces created within the staples  10030  positioned within the inner layer  14520   a , for example. In various other embodiments, any other suitable arrangement of layers, materials, and/or material properties could be utilized. In any event, in various embodiments, the layers  14520   a - 14520   c  of the tissue thickness compensator  14520  can be configured to remain attached to one another after they have been implanted. In certain other embodiments, the layers  14520   a - 14520   c  of the tissue thickness compensator  14520  can be configured to detach from one another after they have been implanted. In at least one such embodiment, the layers  14520   a - 14520   c  can be bonded together utilizing one or more bioabsorbable adhesives which can initially hold the layers together and then allow the layers to release from one another over time. 
     As described above, a tissue thickness compensator of a staple cartridge, such as tissue thickness compensator  14520 , for example, can comprise a plurality of longitudinal layers. In various other embodiments, referring now to  FIG. 369 , a staple cartridge can comprise a tissue thickness compensator, such as tissue thickness compensator  14620 , for example, which can comprise a plurality of horizontal layers. In at least one such embodiment, the tissue thickness compensator  14620  can comprise a first, or bottom, layer  14620   a , a second, or intermediate, layer  14620   b  attached to the bottom layer  14620   a , and a third, or top, layer  14620   c  attached to the intermediate layer  14620   b . In various embodiments, the first layer  14620   a  can comprise a flat, or substantially flat, bottom surface  14626   a  and a triangular, or pyramidal, top surface  14625   a , for example. In at least one such embodiment, the second layer  14620   b  can comprise a triangular, or pyramidal, bottom surface  14626   b  which can be configured to parallel and abut the top surface  14625   a  of the first layer  14620   a . Similar to the above, the second layer  14620   b  can comprise a triangular, or pyramidal, top surface  14625   b  which can parallel and abut a bottom triangular, or pyramidal, bottom surface  14626   c  of the third layer  14620   c , for example. In various embodiments, the top surface of the third layer  14626   c  can comprise a flat, or at least substantially flat, tissue-contacting surface  14621 . Also similar to the above, the tissue thickness compensator  14620  can be configured to at least partially store six rows of staples, such as staples  10030 , for example, therein wherein a firing member can transect the tissue thickness compensator  14620  between the two innermost staple rows along a path extending through axis  14629 , for example. Similar to the above, each layer  14620   a ,  14620   b , and  14620   c  can be comprised of a different material which can comprise different material properties and, as a result of the triangular, or pyramidal, configuration of the layers  14620   a - 14620   c , the tissue thickness compensator  14620  can have different overall properties at various locations therewithin. For example, the outermost rows of staples  10030  may capture more of the third layer  14620   c  than the first layer  14620   a  therein whereas the innermost rows of staples  10030  may capture less of the third layer  14620   c  than the first layer  14620   a  and, as a result, the tissue thickness compensator  14620  may compress the tissue captured within the outermost staples  10030  differently than the tissue captured within the innermost staples  10030 , for example, eventhough the tissue thickness compensator  14620  may have the same, or at least substantially the same, overall thickness thereacross. 
     In various embodiments, referring now to  FIG. 286 , a tissue thickness compensator of a staple cartridge, such as tissue thickness compensator  14720  of staple cartridge  14700 , for example, can comprise voids, pockets, channels, and/or grooves, for example, defined therein which can vary the thickness of the tissue thickness compensator  14720 . In at least one such embodiment, the tissue thickness compensator  14720  can be positioned against the deck surface  14711  of a support portion  14710  of the staple cartridge  14700  such that voids  14723  defined in the bottom surface  14722  of the tissue thickness compensator  14720  can overlie certain staple cavities  10012 , but not others. In various embodiments, the voids  14723  can extend transversely to the knife slot  14715  of the support portion  14710 , perpendicular to the knife slot  14715 , and/or parallel to the knife slot  14715 , for example. In certain embodiments, the voids  14723  can define a tread pattern in the bottom surface  14722  of the tissue thickness compensator  14720 . In any event, when staples, such as staples  10030 , for example, are deployed from the support portion  14710 , referring now to  FIGS. 287 and 288 , certain staples  10030  can capture the tissue thickness compensator  14720  within a region containing a void  14723  while other staples  10030  can capture the tissue thickness compensator  14720  within a region positioned intermediate the voids  14723 . In addition to or in lieu of the above, the tissue thickness compensator  14720  can comprise voids, pockets, channels, and/or grooves, for example, defined in the top, or tissue-contacting, surface  14721 . In certain embodiments, referring now to  FIGS. 366 and 367 , a staple cartridge  14800  can comprise a tissue thickness compensator  14820  which can include a plurality of treads  14823  extending at least one of upwardly from a top surface  14821  of the tissue thickness compensator  14820 , inwardly toward a central groove  14825 , and/or distally toward the distal end of the staple cartridge  14800 , for example. In at least one such embodiment, the treads  14823  can be separated by channels, slots, and/or grooves, such as channels  14824 , for example. In various circumstances, as a result of the above, the overall thickness of the tissue thickness compensator can vary between staple rows and/or vary between the staples within a staple row. In certain circumstances, the treads, or thick portions, can be constructed and arranged such that they can flow in a desire direction, such as inwardly, for example, when the tissue thickness compensator is compressed. 
     In various embodiments, referring now to  FIG. 303 , a staple cartridge, such as staple cartridge  14900 , for example, can comprise a support portion  14910  and, in addition, a tissue thickness compensator  14920  positioned against the support portion  14910 . Similar to the above, the support portion  14910  can comprise staple drivers which can be lifted upwardly by a staple-deploying sled in order to lift staples, such as staples  10030 , for example, at least partially positioned within the support portion  14910  toward an anvil, such as anvil  10060 , for example, positioned opposite the staple cartridge  14900 . In certain embodiments, the support portion  14910  can comprise six rows of staple cavities, such as two outer rows of staple cavities, two inner rows of staple cavities, and two intermediate rows of staple cavities positioned intermediate the inner rows and the outer rows, for example, wherein the anvil  10060  can comprise six rows of forming pockets  10062  aligned, or at least substantially aligned, with the staple cavities. In various embodiments, the inner rows of staple cavities can include staple drivers  14940   a  positioned therein, the intermediate rows of staple cavities can include staple drivers  14940   b  positioned therein, and the outer rows of staple cavities can include staple drivers  14940   c  positioned therein, wherein each of the staple drivers  14940   a  can include a cradle  14949   a  configured to support a staple  10030 , wherein each of the staple drivers  14940   b  can include a cradle  14949   b  configured to support a staple  10030 , and wherein each of the staple drivers  14940   c  can include a cradle  14949   c  configured to support a staple  10030 . In their unfired positions, i.e., when the staple drivers  14940   a - 14940   c  are sitting on driver supports  14926  which extend underneath the support portion  14910 , the cradles  14949   a  of the staple drivers  14940   a  can be positioned closer to the anvil  10060  than the cradles  14949   b  of the staple drivers  14940   b  and the cradles  14949   c  of the staple drivers  14940   c . In such a position, a first forming distance can be defined between the cradles  14949   a  and the forming pockets  10062  positioned over the cradles  14949   a , a second forming distance can be defined between the cradles  14949   b  and the forming pockets  10062  positioned over the cradles  14949   b , and a third forming distance can be defined between the cradles  14949   c  and the forming pockets  10062  positioned over the cradles  14949   c , wherein, in various embodiments, the first forming distance can be shorter than the second forming distance and the second forming distance can be shorter than the third forming distance, for example. When the staple drivers  14940   a - 14940   c  are moved from their unfired positions ( FIG. 303 ) to their fired positions, each staple driver  14940   a - 14940   c  can be moved upwardly an equal, or an at least substantially equal, distance toward the anvil  10060  by the staple-deploying sled such that the first drivers  14940   a  drive their respective staples  10030  to a first formed height, the second drivers  14940   b  drive their respective staples  10030  to a second formed height, and the third drivers  14940   c  drive their respective staples  10030  to a third formed height, wherein the first formed height can be shorter than the second formed height and the second formed height can be shorter than the third formed height, for example. Various other embodiments are envisioned in which the first staple drivers  14940   a  are displaced upwardly a first distance, the second staple drivers  14940   b  are displaced upwardly a second distance, and the third staple drivers  14940   c  are displaced upwardly a third distance, wherein one or more of the first distance, the second distance, and the third distance can be different. 
     In various embodiments, referring again to  FIG. 303 , the deck surface  14911  of the support portion  14910  can vary in height with respect to the tissue-contacting surface  10061  of the anvil  10060 . In certain embodiments, this height variation can occur laterally and, in at least one embodiment, the height of the deck surface  14911  surrounding the inner rows of staple cavities can be higher than the deck surface  14911  surrounding the outer rows of staple cavities, for example. In various embodiments, the bottom surface  14922  of the tissue thickness compensator  14920  can be configured to parallel, or at least substantially parallel, the deck surface  14911  of the support portion  14910 . Further to the above, the tissue thickness compensator  14920  can also vary in thickness wherein, in at least one embodiment, the top, or tissue-contacting, surface  14921  of the tissue thickness compensator  14920  can slope inwardly from the outside or lateral edges thereof. In at least one such embodiment, as a result of the above, the tissue thickness compensator  14920  can be thinner in a region positioned over the inner rows of staple cavities and thicker in a region positioned over the outer rows of staple cavities, for example. In various embodiments, referring now to  FIG. 304 , the deck surface of a support portion  15010  can comprise a stepped deck surface, for example, wherein the highest steps of the stepped surface can surround the inner rows of staple cavities and the lowest steps of the stepped surface can surround the outer rows of staple cavities, for example. In at least one such embodiment, steps having an intermediate height can surround the intermediate rows of staple cavities. In certain embodiments, a tissue thickness compensator, such as tissue thickness compensator  15020 , for example, can comprise a bottom surface which can parallel and abut the deck surface of the support portion  15010 . In at least one embodiment, the top, or tissue-contacting, surface  15021  of the tissue thickness compensator can comprise an arcuate, parabolic, and/or curved surface, for example, which, in at least one such embodiment, can extend from a first lateral side of the tissue thickness compensator  15020  to a second lateral side of the tissue thickness compensator  15020  with an apex aligned, or at least substantially aligned, with the center of the staple cartridge  15000 , for example. In various embodiments, referring now to  FIG. 299 , a staple cartridge  15300 , for example, can comprise a support portion  15310 , a plurality of staple drivers  15340  movably positioned within staple cavities defined in the support portion  15310 , and a tissue thickness compensator  15320  positioned above the deck surface  15311  of the support portion  15310 . The staple cartridge  15300  can further comprise one or more bottom pan portions  15326  which can be attached to the support portion  15310  and extend around the bottom of the support portion  15310  and support the drivers  15340 , and staples  15330 , in their unfired positions. As a staple-deploying sled is advanced through the staple cartridge, the sled can also be supported by the bottom pan portions  15326  as the sled lifts the staple drivers  15340  and the staples  15330  upwardly through the tissue thickness compensator  15320 . In at least one embodiment, the tissue thickness compensator  15320  can comprise a first, or inner, portion  15322   a  positioned over an inner row of staple cavities, a second, or intermediate portion  15322   b  positioned over an intermediate row of staple cavities, and a third, or outer, portion  15322   c  positioned over a row of staple cavities, wherein the inner portion  15322   a  can be thicker than the intermediate portion  15322   b  and the intermediate portion  15322   b  can be thicker than the outer portion  15322   c , for example. In at least one embodiment, the tissue thickness compensator  15320  can comprise longitudinal channels, for example, defined therein which can create the thinner portions  15322   b  and  15322   c  of the tissue thickness compensator  15320 . In various alternative embodiments, the longitudinal channels can be defined in the top surface and/or the bottom surface of a tissue thickness compensator. In at least one embodiment, the top surface  15321  of the tissue thickness compensator  15320  can comprise a flat, or at least substantially flat, surface, for example. 
     In various embodiments, referring now to  FIG. 296 , a staple cartridge can comprise a tissue thickness compensator, such as tissue thickness compensator  15120 , for example, which can comprise a plurality of portions having different thicknesses. In at least one embodiment, the tissue thickness compensator  15120  can comprise a first, or inner, portion  15122   a  which can have a first thickness, second, or intermediate, portions  15122   b  extending from the first portion  15122   b  which can each have a second thickness, and third, or outer, portions  15122   c  extending from the second portions  15122   b  which can each have a third thickness. In at least one such embodiment, the third thickness can be thicker than the second thickness and the second thickness can be thicker than the first thickness, for example, although any suitable thicknesses could be utilized in various other embodiments. In various embodiments, the portions  15122   a - 15122   c  of the tissue thickness compensator  15120  can comprise steps having different thickness. In at least one embodiment, similar to the above, a staple cartridge can comprise several rows of staples  10030  and a plurality of staple drivers having different heights which can deform the staples  10030  to different formed heights. Also similar to the above, the staple cartridge can comprise first staple drivers  15140   a  which can drive the staples  10030  supported thereon to a first formed height, second staple drivers  15140   b  which can drive the staples  10030  supported thereon to a second formed height, and third staple drivers which can drive the staples  10030  supported thereon to a third formed height, wherein the first formed height can be shorter than the second formed height and the second formed height can be shorter than the third formed height, for example. In various embodiments, as illustrated in  FIG. 296 , each staple  10030  can comprise the same, or substantially the same, unformed, or unfired, height. In certain other embodiments, referring now to  FIG. 296A , the first drivers  15140   a , the second drivers  15140   b , and/or the third drivers  15140   c  can support staples having different unformed heights. In at least one such embodiment, the first staple drivers  15140   a  can support staples  15130   a  having a first unformed height, the second staple drivers  15140   b  can support staples  15130   b  having a second unformed height, and the third staple drivers  15140   c  can support staples  15130   c  having a third unformed height, wherein the first unformed height can be shorter than the second unformed height and the second unformed height can be shorter than the third unformed height, for example. In various embodiments, referring again to  FIG. 296A , the tips of the staples  15130   a ,  15130   b , and/or  15130   c  can lie, or at least substantially lie, in the same plane while, in other embodiments, the tips of the staples  15130   a ,  15130   b , and/or  15130   c  may not lie in same plane. In certain embodiments, referring now to  FIG. 297 , a staple cartridge can include a tissue thickness compensator  15220  having a plurality of portions having different thickness which can be implanted against the tissue T by the staples  15130   a ,  15130   b , and  15130   c , as described above. In at least one embodiment, referring now to  FIG. 298 , the staples  15130   a ,  15130   b , and/or  15130   c  can be deformed to different formed heights wherein the first staples  15130   a  can be formed to a first formed height, the second staples  15130   b  can be formed to a second formed height, and the third staples  15130   c  can be formed to a third formed height, and wherein the first formed height can be shorter than the second formed height and the second formed height can be shorter than the third formed height, for example. Other embodiments are envisioned in which the staples  15130   a ,  15130   b , and  15130   c  can be formed to any suitable formed heights and/or any relative formed heights. 
     In various embodiments, as described above, the anvil of a surgical stapling instrument can be moved between an open position and a closed position. In such circumstances, the tissue-contacting surface of the anvil can be moved into its final, or forming, position as the anvil is moved into its closed position. Once the anvil is in its closed position, in certain embodiments, the tissue-contacting surface may no longer be adjustable. In certain other embodiments, referring now to  FIG. 351 , a surgical stapler, such as surgical stapler  15500 , for example, can comprise an anvil channel  15560  and an adjustable tissue-contacting anvil adjustment plate  15561  positioned within the anvil channel  15560 . In such embodiments, the anvil plate  15561  can be raised and/or lowered within the anvil channel  15560  in order to adjust the position of the tissue-contacting surface of the anvil plate  15561  relative to a staple cartridge positioned opposite the anvil plate  15561 . In various embodiments, the surgical stapler  15500  can comprise an adjustment slide  15564  which, referring to  FIGS. 356 and 357 , can be slid intermediate the anvil channel  15560  and the anvil plate  15561  in order to control the distance between the anvil plate  15561  and the staple cartridge. In certain embodiments, referring again to  FIGS. 351 and 352 , the surgical stapler  15500  can further comprise an actuator  15562  coupled to the adjustment slide  15564  which can be slid proximally in order to slide the adjustment slide  15564  proximally and/or slid distally in order to slide the adjustment slide  15564  distally. In various embodiments, referring again to  FIGS. 356 and 357 , the actuator  15562  can be slid between two or more pre-defined positions in order to adjust the anvil plate  15561  between two or more positions, respectively. In at least one embodiment, such pre-defined positions can be demarcated on the surgical stapler  15500  as demarcations  15563  ( FIG. 351 ), for example. In certain embodiments, referring to  FIG. 357 , the adjustment slide  15564  can comprise a plurality of support surfaces, such as first support surface  15565   a , second support surface  15565   b , and third support surface  15565   c , for example, which can be aligned with a plurality of plate positioning surfaces, such as first positioning surface  15569   a , second positioning surface  15569   b , and third positioning surface  15569   c , respectively, on the backside of the anvil plate  15561  in order to position the anvil plate  15561  in a first position. In order to position the anvil plate  15561  in a second position, the actuator  15562  and the slide  15564  can be slid proximally, for example, in order to realign the support surfaces  15565   a - 15565   c  of the slide  15564  relative to the positioning surfaces  15569   a - 15569   c  of the anvil plate  15561 . More particularly, referring to  FIG. 356 , the slide  15564  can be slid distally such that the first support surface  15565   a  of the slide  15564  can be positioned behind the second positioning surface  15569   b  of the anvil plate  15561  and such that the second support surface  15565   b  of the slide  15564  can be positioned behind the third positioning surface  15569   c  of the anvil plate  15561  in order to move the anvil plate  15561  closer to the staple cartridge. When the anvil plate  15561  is moved from its first position to its second position, in such circumstances, the adjustable anvil plate  15561  can further compress the tissue T positioned between the anvil plate  15561  and the staple cartridge. In addition to the above, the formed height of the staples can be controlled by the position of the anvil plate  15561  relative to the staple cartridge as the forming pockets defined in the anvil plate  15561  will move closer to and/or further away from the staple cartridge when the anvil plate  15561  is adjusted. Although only two positions are discussed above, the slide  15564  can be slid into a suitable number of positions to move the anvil plate  15561  closer to and/or away from the staple cartridge. In any event, once the anvil plate  15561  has been suitably positioned, a staple-deploying sled  15550  can be slid distally within the staple cartridge in order to lift staple drivers  15540  and staples  15530  toward the anvil plate  15561  and staple the tissue T, as illustrated in  FIG. 354 . Similar surgical staplers are disclosed in U.S. patent application Ser. No. 13/036,647, entitled SURGICAL STAPLING INSTRUMENT, which was filed on Feb. 28, 2011, now U.S. Pat. No. 8,561,870, the entire disclosure of which is incorporated by reference herein. 
     In various embodiments, referring now to  FIG. 353 , a staple cartridge can be positioned within a staple cartridge channel  15570  of the surgical stapler  15500  which can comprise a tissue thickness compensator, such as tissue thickness compensator  15520 , for example. When the anvil plate  15561  is moved toward the staple cartridge, as described above, the anvil plate  15561  can compress the tissue thickness compensator  15520  and/or the tissue T positioned intermediate the anvil plate  15561  and the tissue thickness compensator  15520 . As the staples  15530  are deployed from the staple cartridge, referring to  FIG. 355 , the staples  15530  can compress and implant the tissue thickness compensator  15520  against the tissue T. In various embodiments, when the anvil plate  15561  is positioned against the slide  15564  and tissue has not yet been placed between the anvil plate  15561  and the tissue thickness compensator  15520 , a gap can be defined between the anvil plate  15561  and the top surface  15521  of the tissue thickness compensator  15520  when the anvil plate  15561  is in a first position. When the anvil plate  15561  is moved into a second position, the anvil plate  15561  can contact the tissue thickness compensator  15520 . In various alternative embodiments, when the anvil plate  15561  is positioned against the slide  15564  and tissue has not yet been placed between the anvil plate  15561  and the tissue thickness compensator  15520 , a gap can be defined between the anvil plate  15561  and the top surface  15521  of the tissue thickness compensator  15520  when the anvil plate  15561  is in a first position and/or a second position. In at least one such embodiment, the anvil plate  15561  may not come into contact with the tissue thickness compensator  15520 . In further alternative embodiments, when the anvil plate  15561  is positioned against the slide  15564  and tissue has not yet been placed between the anvil plate  15561  and the tissue thickness compensator  15520 , the anvil plate  15561  can be in contact with the top surface  15521  of the tissue thickness compensator  15520  regardless of whether the anvil plate  15561  is in a first position and/or a second position, for example. Although only two positions for the anvil plate  15611  are described herein, the anvil plate  15611  may be positioned, or indexed, into any suitable number of positions. 
     In various embodiments, as a result of the above, a surgical stapling instrument can comprise means for adjusting the formed height of the staples which can, in various circumstance, compensate for different tissue thicknesses. In addition, the surgical stapling instrument can comprise other means for compensating for different tissue thicknesses and/or thickness variations within the tissue, for example. In at least one such embodiment, the anvil plate  15561  can be adjusted upwardly, or away, from the opposing staple cartridge to increase the formed, or fired, height of the staples. Correspondingly, the anvil plate  15561  can be adjusted downwardly, or toward, the opposing staple cartridge to decrease the formed, or fired, height of the staples. In various embodiments, the adjustment of the anvil plate  15561 , for example, can adjust the gap between the forming pockets defined in the anvil plate  15561  and the fired height of the staple drivers or, more specifically, the fired height of the staple driver cradles, for example. Even with such a capacity to adjust the formed height of the staples to account for thicker and/or thinner tissue, for example, a tissue thickness compensator can also compensate for thicker and/or thinner tissue and/or compensate for thickness variations within the tissue, as described above. In such embodiments, a surgeon can be afforded with several compensation means within the same surgical stapling instrument. 
     As described above and illustrated in several embodiments, a surgical stapling instrument can utilize a staple cartridge having a linear arrangement of staple cavities and staples wherein a firing member can be advanced distally through the staple cartridge to deploy the staples from the staple cavities. In certain embodiments, a staple cartridge can comprise rows of staple cavities and staples which are curved. In at least one embodiment, referring now to  FIGS. 345 and 346 , a surgical stapling instrument, such as stapler  15600 , for example, can comprise one or more circular or annular rows of staple cavities defined in a circular or annular support portion  15610 . Such circular staple rows can comprise a circular row of inner staple cavities  15612  and a circular row of outer staple cavities  15613 , for example. In at least one such embodiment, the circular rows of staple cavities can surround a circular or annular aperture  15615  defined in the stapler  15600  which can house a circular or annular knife movably positioned therein. In use, tissue can be positioned against the deck surface  15611  of the support portion  15610  and an anvil (not illustrated) can be assembled to the surgical stapler  15600  via an actuator extending through and/or positioned within the aperture  15615  such that, when the actuator is actuated, the anvil can be clamped toward the support portion  15610  and compress the tissue against the deck surface  15611 . Once the tissue has been sufficiently compressed, the staples positioned within the staple cavities  15612  and  15613  can be ejected from the support portion  15610  and through the tissue such that the staples can contact the anvil and be sufficiently deformed to capture the tissue therein. As the staples are being fired and/or after the staples have been fired, the circular knife can be advanced to transect the tissue. Thereafter, the anvil can be moved away from the support portion  15610  and/or detached from the surgical stapler  15600  such that the anvil and the surgical stapler  15600  can be removed from the surgical site. Such surgical staplers  15600  and such surgical techniques, in various embodiments, can be utilized to join two portions of a large intestine, for example. In various circumstances, the circular staple lines may be configured to hold the portions of the large intestine together while the tissue heals and, at the same time, permit the portions of the large intestine to resiliently expand. Similar surgical stapling instruments and surgical techniques are disclosed in U.S. Pat. No. 5,285,945, entitled SURGICAL ANASTOMOSIS STAPLING INSTRUMENT, which issued on Feb. 15, 1994, the entire disclosure of which is incorporated by reference herein. 
     In various embodiments, further to the above, a tissue thickness compensator may be positioned against and/or attached to the support portion  15610  of the surgical stapler  15600 , for example. In at least one embodiment, the tissue thickness compensator can be comprised of a circular or annular ring of material comprising an inner radius and an outer radius, for example. In certain circumstances, tissue can be positioned against this ring of material and, when the anvil is used to move the tissue toward the support portion  15610 , the tissue thickness compensator can be compressed between the tissue and the deck surface  15611 . During use, the staples can be fired through the tissue thickness compensator and the tissue such that the staples can contact the anvil and deform to their fired position to capture portions of the tissue and the tissue thickness compensator within the staples. In various circumstances, further to the above, the ring of material comprising the tissue thickness compensator must be sufficiently resilient to permit the portions of the large intestine surrounding the staple lines to expand. In various embodiments, referring again to  FIGS. 345 and 346 , a flexible tissue thickness compensator  15620  can comprise a circular or annular flexible inner ring  15624 , for example, which, in at least one embodiment, can define a circular or annular aperture  15625 . In certain embodiments, the inner ring  15624  may be configured such that it is not captured within staples deployed from the surgical stapler  15600 ; rather, in at least one embodiment, the inner ring  15624  may be positioned radially inwardly with respect to the inner row of staple cavities  15612 . In at least one such embodiment, the tissue thickness compensator  15620  can comprise a plurality of tags, such as inner tags  15622  and outer tags  15623 , for example, extending therefrom such that the tags can be at least partially captured within the staples as they are being deformed. More particularly, referring primarily to  FIG. 345 , each inner tag  15622  can comprise a head which is positioned over a staple cavity  15612  defined in the surgical stapler  15600  wherein the head can be attached to the inner ring  15624  by a neck  15626 , for example, and, similarly, each outer tag  15623  can comprise a head which is positioned over a staple cavity  15613  defined in the surgical stapler  15600  wherein the head can be attached to the inner ring  15624  by a neck  15627 , for example. In various embodiments, the heads of the inner tags  15622  and the outer tags  15623  can comprise any suitable shape, such as round, oval, and/or elliptical, for example. The necks  15626  and/or  15627  can also comprise any suitable shape wherein, in at least one embodiment, the necks  15627  connecting the heads of the outer tags  15623  to the inner ring  15624  can be configured to extend between adjacent inner staple cavities  15612  in the support portion  15610  such that the necks  15627  are not captured within the staples deployed from the inner staple cavities  15612 . 
     In various embodiments, referring now to  FIGS. 347 and 348 , a flexible tissue thickness compensator  15720  can comprise a circular or annular flexible outer ring  15724 , for example. In certain embodiments, the outer ring  15724  may be configured such that it is not captured within staples deployed from the surgical stapler  15600 ; rather, in at least one embodiment, the outer ring  15724  may be positioned radially outwardly with respect to the outer row of staple cavities  15613 . In at least one such embodiment, the tissue thickness compensator  15720  can comprise a plurality of tags, such as inner tags  15622  and outer tags  15623 , for example, extending therefrom such that the tags can be at least partially captured within the staples as they are being deformed. More particularly, referring primarily to  FIG. 347 , each inner tag  15622  can comprise a head which is positioned over a staple cavity  15612  defined in the surgical stapler  15600  wherein the head can be attached to the outer ring  15724  by a neck  15726 , for example, and, similarly, each outer tag  15623  can comprise a head which is positioned over a staple cavity  15613  defined in the surgical stapler  15600  wherein the head can be attached to the outer ring  15724  by a neck  15727 , for example. In various embodiments, the heads of the inner tags  15622  and the outer tags  15623  can comprise any suitable shape, such as round, oval, and/or elliptical, for example. The necks  15726  and/or  15727  can also comprise any suitable shape wherein, in at least one embodiment, the necks  15726  connecting the heads of the inner tags  15622  to the outer ring  15724  can be configured to extend between adjacent outer staple cavities  15613  such that the necks  15726  are not captured within the staples deployed from the outer staple cavities  15613 . In certain alternative embodiments, a tissue thickness compensator can comprise a circular or annular flexible inner ring, a circular or annular flexible outer ring, and, in addition, a plurality of tags which can be connected to the inner ring and/or the outer ring. In at least one embodiment, certain tags can be connected to the inner ring and certain other tags can be connected to the outer ring. In certain embodiments, at least some of the tags can be connected to both the inner ring and the outer ring. In any event, further to the above, the inner ring  15624  of the tissue thickness compensator  15620 , the outer ring  15724  of the tissue thickness compensator  15720 , and/or any other suitable tissue thickness compensator, can be configured to resiliently expand and/or contract in order to accommodate the expansion and/or contraction of the tissue that it has been implanted against. Furthermore, although various embodiments are described herein as comprising circular or annular support rings, a tissue thickness compensator can comprise any suitably-shaped support structure for connecting the tags thereto. In various embodiments, further to the above, the circular knife advanced by the surgical stapler to cut the tissue captured between the anvil and the support portion can also cut the buttress material. In at least one such embodiment, the knife can separate the inner support ring from the tags by cutting the necks thereof, for example. 
     In various embodiments, further to the above, a tissue thickness compensator can comprise detachable and/or relatively movable positions which can be configured to allow the tissue thickness compensator to expand and/or contract in order to accommodate the movement of the tissue that it has been implanted against. Referring now to  FIGS. 349 and 350 , a circular or annular tissue thickness compensator  15820  can be positioned against and/or supported by the deck surface  15611  of the surgical stapler  15600  which can be held in an unexpanded position ( FIG. 349 ) as it is being implanted against the tissue and, after the tissue thickness compensator  15820  has been implanted, the tissue thickness compensator  15820  can be configured to expand outwardly, as illustrated in  FIG. 350 . In various embodiments, the tissue thickness compensator  15820  can comprise a plurality of arcuate portions  15822  which can be connected together by an inner ring  15824 , for example. In at least one embodiment, the arcuate portions  15822  can be separated from one another by seams  15828 . In at least one other embodiment, the arcuate portions  15822  may be connected to one another wherein, in at least one such embodiment, an arrangement of perforations may permit the arcuate portions  15822  to separate from one another. In either event, in various embodiments, the arcuate portions  15822  can each comprise interlocking features, such as projections  15826  and notches  15823 , for example, which can co-operate to limit relative movement between the arcuate portions  15822  prior to the tissue thickness compensator  15820  being implanted. Further to the above, each arcuate portion  15822  can be connected to the inner ring  15824  by one or more connectors  15827 , for example, which can be configured to releasably hold the arcuate portions  15822  in position. After the staples, such as staples  10030 , for example, stored within the support portion  15610  have been utilized to implant the tissue thickness compensator  15620  against the tissue, referring primarily to  FIG. 350 , the connectors  15827  can detach from the inner ring  15824  and allow the tissue thickness compensator  15820  to at least partially expand to accommodate movement within the underlying tissue. In various circumstances, all of the arcuate portions  15822  may detach from the inner ring  15824  while, in other circumstances, only some of the arcuate portions  15822  may detach from the inner ring  15824 . In certain alternative embodiments, the arcuate portions  15822  can be connected by flexible sections which can permit the arcuate portions  15822  to move relative to each other but not detach from one another. In at least one such embodiment, the flexible sections may not receive staples therein and can be configured to stretch and/or contract to accommodate the relative movement of the arcuate portions  15822 . In the embodiment illustrated in  FIGS. 349 and 350 , the tissue thickness compensator  15820  can comprise eight arcuate portions  15822 , for example. In certain other embodiments, a tissue thickness compensator can comprise any suitable number of arcuate portions, such as two or more arcuate portions, for example. 
     Further to the above, a tissue thickness compensator  15620 ,  15720 , and/or  15820 , for example, can be configured to compensate for thicker and/or thinner tissue captured between the anvil and the support portion  15610  of the surgical instrument  15600 . In various embodiments, similar to the above, the formed, or fired, height of the staples can be adjusted by moving the anvil toward and/or away from the support portion  15610 . More particularly, the anvil can be moved closer to the support portion  15610  to decrease the formed height of the staples while, correspondingly, the anvil can be moved further away from the support portion  15610  to increase the formed height of the staples. In such embodiments, as a result, a surgeon can adjust the anvil away from the support portion  15610  to account for thick tissue and toward the support portion  15610  to account for thin tissue. In various other circumstances, the surgeon may decide not to adjust the anvil at all and rely on the tissue thickness compensator to account for the thinner and/or thicker tissue. In various embodiments, as a result, the surgical instrument  15600  can comprise at least two means for compensating for different tissue thicknesses and/or variations in the tissue thickness. 
     In various embodiments, as described above, a tissue thickness compensator can be attached to a support portion of a staple cartridge. In certain embodiments, the bottom surface of the tissue thickness compensator can comprise one of a layer of hooks or a layer of loops while a deck surface on the support portion can comprise the other one of the layer of hooks and the layer of loops. In at least one such embodiment, the hooks and the loops can be configured to engage one another and releasably retain the tissue thickness compensator to the support portion. In various embodiments, each hook can comprise an enlarged head extending from a neck, for example. In certain embodiments, a plurality of pads comprising the loops, for example, can be bonded to the bottom surface of the tissue thickness compensator while a plurality of pads comprising the hooks can be bonded to the deck surface of the support portion. In at least one embodiment, the support portion can comprise one or more apertures and/or recesses, for example, which can be configured to receive an insert therein comprising hooks and/or loops. In addition to or in lieu of the above, a tissue thickness compensator can be removably mounted to an anvil utilizing such hook and loop arrangements, for example. In various embodiments, the hooks and loops can comprise fibrous surfaces, for example. 
     In various embodiments, as described above, a staple cartridge can comprise a support portion and a tissue thickness compensator attached to the support portion. In certain embodiments, as also described above, the support portion can comprise a longitudinal slot configured to receive a cutting member therein and the tissue thickness compensator can comprise a retention member that can be retained in the longitudinal slot. In at least one embodiment, referring now to  FIG. 386 , a staple cartridge  16000  can comprise a support portion  16010  including a deck surface  16011  and a longitudinal slot  16015 . The staple cartridge  16000  can further comprise a tissue thickness compensator  16020  positioned above the deck surface  16011 . In various embodiments, the tissue thickness compensator  16020  can include a longitudinal retention member  16025  which extends downwardly into the longitudinal slot  16015 . In at least one such embodiment, the retention member  16025  can be pressed into the slot  16015  such that the interaction between the retention member  16025  and the slot  16015  can resist relative movement between the support portion  16010  and the tissue thickness compensator  16020 . In various embodiments, the body of the tissue thickness compensator  16020  can be comprised of a first material and the retention member  16025  can be comprised of a second, or different, material. In certain embodiments, the body of the tissue thickness compensator  16020  can be comprised of a material having a first durometer and the retention member  16025  can be comprised of a material having a second durometer, wherein the second durometer can be higher than the first durometer, for example. In use, in at least one embodiment, the staples  10030  can be pushed upwardly by staple drivers  10040  such that the tips of the staples  10030  can push through the body of the tissue thickness compensator  16020  and emerge from the tissue contacting surface  16021  and capture at least a portion of the tissue thickness compensator  16020  against the targeted tissue. In various embodiments, a cutting member passing through the slot  16015  can transect the retention member  16025  as the staples  10030  are being deployed. Once the tissue thickness compensator  16020  has been implanted, in various embodiments, the retention member  16025  can be pulled out of the slot  16015 . In certain other embodiments, the body of the tissue thickness compensator  16020  can be configured to detach from the retention member  16025 . 
     Referring now to  FIGS. 387 and 389 , a staple cartridge  17000  can comprise a support portion  17010  including a deck surface  17011  and a longitudinal slot  17015 . The staple cartridge  17000  can further comprise a tissue thickness compensator  17020  positioned above the deck surface  17011 . In various embodiments, the tissue thickness compensator  17020  can include a longitudinal retention member  17025  which extends downwardly into the longitudinal slot  17015 . In at least one such embodiment, the retention member  17025  can be pressed into the slot  17015  such that the interaction between the retention member  17025  and the slot  17015  can resist relative movement between the support portion  17010  and the tissue thickness compensator  17020 . In various embodiments, the retention member  17025  can extend through the entirety of the tissue thickness compensator  17020  to the top surface  17021  thereof wherein body portions  17024  of the tissue thickness compensator  17020  can be attached to opposite sides of the retention member  17025 . In at least one such embodiment, the retention member  17025  can also be configured to resist the lateral deflection, for example, of the tissue thickness compensator  17020 . In various embodiments, the body portions  17024  can be comprised of a first material and the retention member  17025  can be comprised of a second, or different, material. In certain embodiments, the body portions  17024  can be comprised of a material having a first durometer and the retention member  17025  can be comprised of a material having a second durometer, wherein the second durometer can be higher than the first durometer, for example. In various embodiments, further to the above, a cutting member passing through the slot  17015  can transect the retention member  17025  as the staples  10030  are being deployed. Once the tissue thickness compensator  17020  has been implanted, in various embodiments, the retention member  17025  can be pulled out of the slot  17015 . In certain other embodiments, the body portions  17024  can be configured to detach from the retention member  17025 . 
     Referring now to  FIG. 388 , a staple cartridge  18000  can comprise a support portion  18010  including a deck surface  18011  and a longitudinal slot  18015 . The staple cartridge  18000  can further comprise a tissue thickness compensator  18020  positioned above the deck surface  18011 . In various embodiments, the tissue thickness compensator  18020  can include a longitudinal retention member  18025  which extends downwardly into the longitudinal slot  18015 . In at least one such embodiment, the retention member  18025  can be pressed into the slot  18015  such that the interaction between the retention member  18025  and the slot  18015  can resist relative movement between the support portion  18010  and the tissue thickness compensator  18020 . In various embodiments, the retention member  18025  can extend through the entirety of the tissue thickness compensator  18020  to the top surface  18021  thereof wherein body portions  18024  of the tissue thickness compensator  18020  can be attached to opposite sides of the retention member  18025 . In at least one embodiment, the retention member  18025  can comprise an enlarged portion  18026  which can be received in a cavity  18016  defined in the slot  18015 . In at least one such embodiment, the enlarged portion  18026  can resist the withdrawal of the retention member  18025  from the slot  18015 . 
     In various embodiments, referring now to  FIGS. 390-393 , a tissue thickness compensator assembly  19300  for use in a surgical instrument  19000  may include a first tissue thickness compensator  19302 , a second tissue thickness compensator  19304 , and a hinge portion  19306 . The surgical instrument  19000  may comprise a surgical cutting and stapling instrument, for example. In various embodiments, the first tissue thickness compensator  19302  can be positioned relative to an anvil  19100  of the surgical instrument  19000  and the second tissue thickness compensator  19304  can be positioned relative to an staple cartridge  19200  of the surgical instrument  19000 . In various embodiments, the first tissue thickness compensator  19302  and the second tissue thickness compensator  19304  may be connected to each other by the hinge portion  19306 . The hinge portion  19306  can position the first tissue thickness compensator  19302  relative to the second tissue thickness compensator  19304 . The hinge portion  19306  may also enable the first tissue thickness compensator  19302  to rotate relative to the second tissue thickness compensator  19304  about the hinge portion  19306 . In various embodiments, the hinge portion  19306  comprises a resilient material that can flex to enable the first tissue thickness compensator  19302  to rotate relative to the second tissue thickness compensator  19304  about the hinge portion  19306 . 
     In at least one embodiment, further to the above, the tissue thickness compensator assembly  19300  can be moved between a relaxed configuration and a flexed configuration. When the tissue thickness compensator assembly  19300  is in its relaxed configuration, in various embodiments, the tissue thickness compensator assembly  19300  can define an angle between the first tissue thickness compensator  19302  and the second tissue thickness compensator  19302  that is greater than or equal to an angle defined between the anvil  19100  and the staple cartridge  19200 . In such embodiments, the tissue thickness compensator assembly  19300  can be flexed about the hinge portion  19306  in order to position the tissue thickness compensator assembly  19300  between the anvil  19100  and the staple cartridge  19200 . After the tissue thickness compensator assembly  19300  has been positioned within the surgical instrument  19000 , the tissue thickness compensator assembly  19300  may be released to allow the tissue thickness compensator assembly  19300  to re-open and position the first tissue thickness compensator  19302  against the anvil  19100  and the second tissue thickness compensator  19304  against the staple cartridge  19200 . In various alternative embodiments, the tissue thickness compensator assembly  19300  can define an angle between the first tissue thickness compensator  19302  and the second tissue thickness compensator  19304  that is less than an angle defined between the anvil  19100  and the staple cartridge  19200 . In at least one such embodiment, the tissue thickness compensator assembly  19300  can be installed on the staple cartridge  19200  in the surgical instrument  19000  in the relaxed configuration. Thereafter, the anvil  19100  may be moved to a closed position. In various circumstances, as a result, the anvil  19100  can contact the first tissue thickness compensator  19302  and move the tissue thickness compensator assembly  19300  to a flexed configuration. 
     Put differently, the hinge portion  19306  includes a shape that defines a relaxed-state angle between the first tissue thickness compensator  19302  and the second tissue thickness compensator  19304 . When a force is applied to the first tissue thickness compensator  19302  and/or the second tissue thickness compensator  19304 , the hinge portion  19306  can flex to change the relaxed-state angle between the first tissue thickness compensator  19302  and the second tissue thickness compensator  19304  to a different angle. When the force is removed, the hinge  19306  can return the first tissue thickness compensator  19302  and the second tissue thickness compensator  19304  to the relaxed-state angle. In various embodiments, a gap can exist between the anvil  19100  and the first tissue thickness compensator  19302  when the assembly  19300  is in its relaxed-state angle. In such an embodiment, the anvil  19100  can be moved toward a closed position to contact the first tissue thickness compensator  19302 . In various embodiments, the relaxed-state angle can bias the first tissue thickness compensator  19302  into contact with the anvil  19100  such that there is no gap between the first tissue thickness compensator  19302  and the anvil  19100 , for example. In various embodiments, as a result, an adhesive may not be required to attach the first tissue thickness compensator  19302  to the anvil  19100  because the bias of the hinge portion  19306  can push the first tissue thickness compensator  19306  into alignment and contact with the anvil  19100 , for example. 
     In various embodiments, referring to  FIG. 392 , the hinge portion  19306  may include a gap, or opening,  19310 . In various embodiments, when the tissue thickness compensator assembly  19300  is installed in the surgical instrument  19000 , the gap  19310  may be aligned with a cutting blade slot, such as slot  19104  shown in  FIG. 392 , of the surgical instrument  19000 . In at least one embodiment, the gap  19310  can reduce the amount of energy required to pass a cutting blade through the first tissue thickness compensator  19302 , the second tissue thickness compensator  19304 , and/or the hinge portion  19306 . In certain embodiments, a surface  19303  of the first tissue thickness compensator  19302  may include an adhesive thereon which can be configured to attach the first tissue thickness compensator  19302  to a surface  19102  of the anvil  19100 . A surface  19305  of the second tissue thickness compensator  19304  may include an adhesive thereon which can be configured to attach the second tissue thickness compensator  19304  to a surface  19202  of the staple cartridge  19200 . Referring to  FIG. 393 , when the staple cartridge  19200  is attached to the surgical instrument  19000 , in various embodiments, the hinge portion  19306  of the tissue thickness compensator assembly  19300  can align the first tissue thickness compensator  19302  relative to the anvil  19100 . 
     As shown in  FIG. 390 , the first tissue thickness compensator  19302  defines a first uncompressed thickness t 1  and the second tissue thickness compensator  19304  defines a second uncompressed thickness t 2 . The first uncompressed thickness t 1  and the second uncompressed thickness t 2  added together defines a total uncompressed thickness t T . In various embodiments, the first uncompressed thickness t 1  can be 50% of the total uncompressed thickness t T  and the second uncompressed thickness also can be 50% of the total uncompressed thickness t T , for example. In various other embodiments, the first uncompressed thickness t 1  can be greater than 50% of the total uncompressed thickness t T . For example, the first uncompressed thickness t 1  can be approximately 60%, 70%, 80%, or 90% of the total uncompressed thickness t T . In various other embodiments, the first uncompressed thickness t 1  can be less than 50% of the total uncompressed thickness t T . For example, the first uncompressed thickness t 1  can be approximately 40%, 30%, 20%, or 10% of the total uncompressed thickness t T . In various embodiments, the second uncompressed thickness t 2  comprises the remainder of the total uncompressed thickness t T . For example, if the first uncompressed thickness t 1  is equal to 70% of the total uncompressed thickness t T , then the second uncompressed thickness t 2  can be equal to 30% of the total uncompressed thickness t T . In the embodiment illustrated in  FIG. 390 , the first tissue thickness compensator and the second tissue thickness compensator can be placed in contact with, or abutting alignment with, one another. In such a position, the relative uncompressed thicknesses can be easily determined. However, the relative uncompressed thicknesses of the first tissue thickness compensator and the second tissue thickness compensator can be evaluated and related even if a gap is defined between them. 
     Referring to  FIG. 391 , the first tissue thickness compensator  19302  and the second tissue thickness compensator  19304  can be compressed to accommodate varying thicknesses of patient tissue T being stapled.  FIG. 391  illustrates a first staple  19204   a , a second staple  19204   b , and a third staple  19204   c  extending through patient tissue T, the first tissue thickness compensator  19302 , and the second tissue thickness compensator  19304 .  FIG. 391  also illustrates the patient tissue T proximate to the first staple  19204   a  as being thicker than the patient tissue T proximate to the third staple  19204   c . As a result, the first tissue thickness compensator  19302  and the second tissue thickness compensator  19304  are more compressed at, or within, the first staple  19204   a  than at, or within, the third staple  19204   c . In various embodiments, the changing compression of the first tissue thickness compensator  19302  and the second tissue thickness compensator  19304  at different staples  19204   a ,  19204   b , and  19204   c  can permit the total thickness of the first tissue thickness compensator  19302 , the second tissue thickness compensator  19304  and the patient tissue T at each staple to be substantially the same. 
     As discussed herein, two or more tissue thickness compensators can be utilized to provide tissue thickness compensation to the tissue being stapled. In various circumstances, a minimum amount, or a desired amount, of tissue thickness compensation may be needed, or desired, for a particular surgical technique. In various circumstances, it may be immaterial whether this minimum tissue thickness compensation is provided by an anvil-based tissue thickness compensator, a staple cartridge-based tissue thickness compensator, or both as long as the combined tissue thickness compensation provided by the tissue thickness compensators is equal to or greater than the minimum, or desired, tissue thickness compensation. With this in mind, in various embodiments, a first tissue thickness compensator can comprise a first fraction of the minimum, or desired, tissue thickness compensation and a second tissue thickness compensator can comprise a second fraction of the minimum, or desired, tissue thickness compensation wherein the sum of the first fraction and the second fraction is equal to or exceeds the minimum, or desired, tissue thickness compensation. In at least one such embodiment, the first tissue thickness compensator can comprise a first uncompressed height and the second tissue thickness compensator can comprise a second uncompressed height wherein the sum of the first uncompressed height and the second uncompressed height can be equal to or larger than the minimum, or desired, tissue thickness compensation. 
     In various embodiments, further to the above, the first tissue thickness compensator can be comprised of a first material and the second tissue thickness compensator can be comprised of a second, or different, material. In at least one such embodiment, the first material and the second material can have different compression characteristics. In certain embodiments, the first thickness of the first material and the second thickness of the second material can be selected in view of the compression characteristics of the materials. For instance, the first material may comprise a first spring stiffness and the second material may comprise a second spring stiffness, wherein the first tissue thickness compensator and the second tissue thickness compensator may, together, define an overall spring stiffness. To arrive at a particular, or desired, overall spring stiffness, the first thickness of the first tissue thickness compensator and the second thickness of the second tissue thickness compensator can be selected such that the aggregate effect of the first and second tissue thickness compensators arrives at the desired overall spring stiffness, for example. 
     Referring to  FIGS. 394-397 , a tissue thickness compensator assembly  19400  can include a first tissue thickness compensator  19402 , a second tissue thickness compensator  19404 , a hinge portion  19406 , and a raised ridge  19408  extending from the first tissue thickness compensator  19402 . The raised ridge  19408  may engage a slot  19104  in the anvil  19100  shown in  FIG. 392 . In certain embodiments, the raised ridge  19408  may be sized slightly larger than the slot  19104  in the anvil  19100  such that the raised ridge  19408  may compress in order to fit in the slot  19104 . The compression of the raised ridge  19408  can hold the raised ridge  19408  in the slot  19104  in the anvil  19100 . In certain embodiments, the raised ridge  19408  may include an adhesive thereon. In various embodiments, the second tissue thickness compensator  19404  also may include a raised ridge that may engage a slot in the staple cartridge. 
     Referring to  FIG. 398 , a tissue thickness compensator assembly  19500  can include a first tissue thickness compensator  19502 , a second tissue thickness compensator  19504 , a hinge portion  19506 , and a raised ridge  19512  that includes lips  19514  and a tapered end  19516 . The raised ridge  19512  can engage a slot in an anvil of a surgical device, such as the slot  10065  shown in  FIGS. 314A and 314B , for example. The tapered end  19516  can guide the raised ridge  19512  into the slot  10065  wherein the lips  19514  of the raised ridge  19512  may extend laterally in the slot  10065 . As a result, the first tissue thickness compensator  19502  can be retained to the anvil. 
     Referring to  FIG. 399 , a tissue thickness compensator assembly  19600  can include a first tissue thickness compensator  19602 , a second tissue thickness compensator  19604 , a hinge portion  19606 , and wings  19612  extending from sides of the first tissue thickness compensator  19602 . The wings  19612  can engage the sides of an anvil, such as sides  19120  and  19122  of the anvil  19100  shown in  FIG. 392 . In various embodiments, the wings  19612  can be spaced apart by an amount that is slightly less than a lateral dimension of the anvil  19100  defined between the sides  19120  and  19122 . As a result, the wings  19612  and the first tissue thickness compensator  19602  can stretch to fit around the sides  19120  and  19122  of the anvil  19100 . The stretching of the first tissue thickness compensator  19602  and the wings  19612  can hold the first tissue thickness compensator  19602  to the anvil  19100 . In various embodiments, the wings  19612  may include an adhesive that adheres to the sides  19120  and  19122  of the anvil  19100 . In various embodiments, the wings  19612  can provide lateral alignment of the first tissue thickness compensator  19602  relative to the anvil  19100 . 
     Referring to  FIG. 400 , a tissue thickness compensator assembly  19700  can include a first tissue thickness compensator  19702 , a second tissue thickness compensator  19704 , a hinge portion  19706 , and an encasement  19720  within the first tissue thickness compensator  19702 . In various embodiments, the encasement  19720  can include an anti-microbial gel, a coagulant, an anti-inflammatory, and/or other suitable biologic agents, for example. In certain embodiments, the encasement  19720  can include a film of material that is opened by staples of the surgical instrument  19000  piercing the film, a knife of the surgical instrument  19000  cutting the film, and/or by contact with liquids dissolving the film, for example. In certain embodiments, the encasement  19720  can include a region of the first tissue thickness compensator  19702  in which the biologic agent is carried. In certain embodiments, the encasement  19720  can encompass the entire first tissue thickness compensator  19702 . In certain embodiments, the second tissue thickness compensator  19704  can include an encasement similar to the encasement  19720  in the first tissue thickness compensator  19704 , for example. 
     In certain embodiments, the tissue thickness compensator assemblies disclosed herein may be installed onto an anvil and staple cartridge of a surgical cutting and stapling instrument using a retainer. In certain embodiments, the tissue thickness compensator assemblies may be provided as part of a replacement end effector assembly, or disposable loading unit, that is attached to a surgical instrument. Referring to  FIGS. 401-403 , in certain embodiments, a replacement end effector assembly  19800  may include a body  19850 , an anvil  19810 , a staple cartridge  19820 , and a tissue thickness compensator assembly  19830 . In various embodiments, the tissue thickness compensator assembly  19830  can include a first tissue thickness compensator  19832  positioned relative to the anvil  19810  and a second tissue thickness compensator  19834  positioned relative to the staple cartridge  19820 . The body  19850  can include a proximal end  19840  that is configured to be attached to a surgical instrument. In use, a surgeon, nurse, and/or technician, for example, can engage the replacement end effector assembly  19800  with an end of a surgical instrument. Such engagement can physically attach the replacement end effector assembly  19800  to the surgical instrument and can also operably connect a firing member within the end effector assembly to a firing member of the surgical instrument. For example, the anvil  19810 , a cutting blade, and/or a staple-firing-sled in the cartridge  19820  can be operably connected to one or more actuators in the surgical instrument. 
     In various embodiments, a tissue thickness compensator assembly can be provided as part of a replacement end effector assembly wherein, in at least one embodiment, the replacement end effector assembly can be prepared in a factory or manufacturing environment. In such an environment, the tissue thickness compensator assembly may not require alignment features because the factory may have alternatives for aligning tissue thickness compensators of the tissue thickness compensator assembly to the end effector for a surgical instrument. For example, in a factory environment, templates, frames, jigs, and/or the like can be used to assist in positioning a tissue thickness compensator assembly relative to the end effector. Robotic machines that can precisely position a tissue thickness compensator assembly relative to the end effector also can be used.  FIGS. 404-406  illustrate a replacement end effector assembly  19900 , which can be similar to the replacement end effector assembly  19800  shown in  FIGS. 403 and 404  in many respects, can include tissue thickness compensators  19932  and  19934  that may not include alignment features shown on tissue thickness compensator assembly  19830 . In at least one embodiment, the tissue thickness compensators  19932  and  19934  may not include a connector, or hinge portion, like hinge portion  19836  of tissue thickness compensator assembly  19830 , for example. 
     In various embodiments, further to the above, a kit may be provided that comprises a variety of tissue thickness compensators having different uncompressed thicknesses. A surgeon, for example, can select a plurality of tissue thickness compensators from the kit wherein the sum of the uncompressed thicknesses of the selected tissue thickness compensators can be greater than or equal to a desired total uncompressed thickness. For example, a surgeon may determine that a total uncompressed thickness of the tissue thickness compensators may need to equal or exceed a certain amount for a given surgical technique and can select one or more tissue thickness compensators from the kit that provides that desired thickness. The surgeon may select a single tissue thickness compensator that provides the desired total uncompressed thickness or, alternatively, two or more tissue thickness compensators that, in combination, provide the desired total uncompressed thickness. 
     In various embodiments, further to the above, a tissue thickness compensator can be comprised of a biocompatible material. The biocompatible material, such as, a foam, may comprise tackifiers, surfactants, fillers, cross-linkers, pigments, dyes, antioxidants and other stabilizers and/or combinations thereof to provide desired properties to the material. In certain embodiments, a biocompatible foam may comprise a surfactant. The surfactant may be applied to the surface of the material and/or dispersed within the material. Without wishing to be bound to any particular theory, the surfactant applied to the biocompatible material may reduce the surface tension of the fluids contacting the material. For example, the surfactant may reduce the surface tension of water contacting the material to accelerate the penetration of water into the material. In various embodiments, the water may act as a catalyst. The surfactant may increase the hydrophilicity of the material. 
     In various embodiments, the surfactant may comprise an anionic surfactant, a cationic surfactant, and/or a non-ionic surfactant. Examples surfactants include, but are not limited to polyacrylic acid, methalose, methyl cellulose, ethyl cellulose, propyl cellulose, hydroxy ethyl cellulose, carboxy methyl cellulose, polyoxyethylene cetyl ether, polyoxyethylene lauryl ether, polyoxyethylene octyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene stearyl ether, polyoxyethylene nonylphenyl ether, dialkylphenoxy poly(ethyleneoxy) ethanol, and polyoxamers, and combinations thereof. In at least one embodiment, the surfactant may comprise a copolymer of polyethylene glycol and polypropylene glycol. In at least one embodiment, the surfactant may comprise a phospholipid surfactant. The phospholipid surfactant may provide antibacterial stabilizing properties and/or disperse other materials in the biocompatible material. In various embodiments, the tissue thickness compensator may comprise at least one medicament. The tissue thickness compensator may comprise one or more of the natural materials, non-synthetic materials, and/or synthetic materials described herein. In certain embodiments, the tissue thickness compensator may comprise a biocompatible foam comprising gelatin, collagen, hyaluronic acid, oxidized regenerated cellulose, polyglycolic acid, polycaprolactone, polyactic acid, polydioxanone, polyhydroxyalkanoate, poliglecaprone, and combinations thereof. In certain embodiments, the tissue thickness compensator may comprise a film comprising the at least one medicament. In certain embodiments, the tissue thickness compensator may comprise a biodegradable film comprising the at least one medicament. In certain embodiments, the medicament may comprise a liquid, gel, and/or powder. In various embodiments, the medicaments may comprise anticancer agents, such as, for example, cisplatin, mitomycin, and/or adriamycin. 
     In various embodiments, the tissue thickness compensator may comprise a biodegradable material to provide controlled elution of the at least one medicament as the biodegradable material degrades. In various embodiments, the biodegradable material may degrade may decompose, or loses structural integrity, when the biodegradable material contacts an activator, such as, for example an activator fluid. In various embodiments, the activator fluid may comprise saline or any other electrolyte solution, for example. The biodegradable material may contact the activator fluid by conventional techniques, including, but not limited to spraying, dipping, and/or brushing. In use, for example, a surgeon may dip an end effector and/or a staple cartridge comprising the tissue thickness compensator comprising the at least one medicament into an activator fluid comprising a salt solution, such as sodium chloride, calcium chloride, and/or potassium chloride. The tissue thickness compensator may release the medicament as the tissue thickness compensator degrades. In certain embodiments, the elution of the medicament from the tissue thickness compensator may be characterized by a rapid initial elution rate and a slower sustained elution rate. 
     In various embodiments, a tissue thickness compensator, for example, can be comprised of a biocompatible material which may comprise an oxidizing agent. In various embodiments, the oxidizing agent may an organic peroxide and/or an inorganic peroxide. Examples of oxidizing agents may include, but are not limited to, hydrogen peroxide, urea peroxide, calcium peroxide, and magnesium peroxide, and sodium percarbonate. In various embodiments, the oxidizing agent may comprise peroxygen-based oxidizing agents and hypohalite-based oxidizing agents, such as, for example, hydrogen peroxide, hypochlorous acid, hypochlorites, hypocodites, and percarbonates. In various embodiments, the oxidizing agent may comprise alkali metal chlorites, hypochlorites and perborates, such as, for example, sodium chlorite, sodium hypochlorite and sodium perborate. In certain embodiments, the oxidizing agent may comprise vanadate. In certain embodiments, the oxidizing agent may comprise ascorbic acid. In certain embodiments, the oxidizing agent may comprise an active oxygen generator. In various embodiments, a tissue scaffold may comprise the biocompatible material comprising an oxidizing agent. 
     In various embodiments, the biocompatible material may comprise a liquid, gel, and/or powder. In certain embodiments, the oxidizing agent may comprise microparticles and/or nanoparticles, for example. For example, the oxidizing agent may be milled into microparticles and/or nanoparticles. In certain embodiments, the oxidizing agent may be incorporated into the biocompatible material by suspending the oxidizing agent in a polymer solution. In certain embodiments, the oxidizing agent may be incorporated into the biocompatible material during the lyophylization process. After lyophylization, the oxidizing agent may be attached to the cell walls of the biocompatible material to interact with the tissue upon contact. In various embodiments, the oxidizing agent may not be chemically bonded to the biocompatible material. In at least one embodiment, a percarbonate dry power may be embedded within a biocompatible foam to provide a prolonged biological effect by the slow release of oxygen. In at least one embodiment, a percarbonate dry power may be embedded within a polymeric fiber in a non-woven structure to provide a prolonged biological effect by the slow release of oxygen. In various embodiments, the biocompatible material may comprise an oxidizing agent and a medicament, such as, for example, doxycycline and ascorbic acid. 
     In various embodiments, the biocompatible material may comprise a rapid release oxidizing agent and/or a slower sustained release oxidizing agent. In certain embodiments, the elution of the oxidizing agent from the biocompatible material may be characterized by a rapid initial elution rate and a slower sustained elution rate. In various embodiments, the oxidizing agent may generate oxygen when the oxidizing agent contacts bodily fluid, such as, for example, water. Examples of bodily fluids may include, but are not limited to, blood, plasma, peritoneal fluid, cerebral spinal fluid, urine, lymph fluid, synovial fluid, vitreous fluid, saliva, gastrointestinal luminal contents, and/or bile. Without wishing to be bound to any particular theory, the oxidizing agent may reduce cell death, enhance tissue viability and/or maintain the mechanical strength of the tissue to tissue that may be damaged during cutting and/or stapling. In various embodiments, the biocompatible material may comprise at least one microparticle and/or nanoparticle. The biocompatible material may comprise one or more of the natural materials, non-synthetic materials, and synthetic materials described herein. In various embodiments, the biocompatible material may comprise particles having a mean diameter of about 10 nm to about 100 nm and/or about 10 μm to about 100 μm, such as, for example, 45-50 nm and/or 45-50 μm. In various embodiments, the biocompatible material may comprise biocompatible foam comprising at least one microparticle and/or nanoparticle embedded therein. The microparticle and/or nanoparticle may not be chemically bonded to the biocompatible material. The microparticle and/or nanoparticle may provide controlled release of the medicament. In certain embodiments, the microparticle and/or nanoparticle may comprise at least one medicament. In certain embodiments, the microparticle and/or nanoparticle may comprise a hemostatic agent, an anti-microbial agent, and/or an oxidizing agent, for example. In certain embodiments, the tissue thickness compensator may comprise a biocompatible foam comprising an hemostatic agent comprising oxidized regenerated cellulose, an anti-microbial agent comprising doxycline and/or Gentamicin, and/or an oxidizing agent comprising a percarbant. In various embodiments, the microparticle and/or nanoparticle may provide controlled release of the medicament up to three days, for example. 
     In various embodiments, the microparticle and/or nanoparticle may be embedded in the biocompatible material during a manufacturing process. For example, a biocompatible polymer, such as, for example, a PGA/PCL, may contact a solvent, such as, for example, dioxane to form a mixture. The biocompatible polymer may be ground to form particles. Dry particles, with or without ORC particles, may be contacted with the mixture to form a suspension. The suspension may be lyophilized to form a biocompatible foam comprising PGA/PCL having dry particles and/or ORC particles embedded therein. 
     In various embodiments, the tissue thickness compensators or layers disclosed herein can be comprised of an absorbable polymer, for example. In certain embodiments, a tissue thickness compensator can be comprised of foam, film, fibrous woven, fibrous non-woven PGA, PGA/PCL (Poly(glycolic acid-co-caprolactone)), PLA/PCL (Poly(lactic acid-co-polycaprolactone)), PLLA/PCL, PGA/TMC (Poly(glycolic acid-co-trimethylene carbonate)), PDS, PEPBO or other absorbable polyurethane, polyester, polycarbonate, Polyorthoesters, Polyanhydrides, Polyesteramides, and/or Polyoxaesters, for example. In various embodiments, a tissue thickness compensator can be comprised of PGA/PLA (Poly(glycolic acid-co-lactic acid)) and/or PDS/PLA (Poly(p-dioxanone-co-lactic acid)), for example. In various embodiments, a tissue thickness compensator can be comprised of an organic material, for example. In certain embodiments, a tissue thickness compensator can be comprised of Carboxymethyl Cellulose, Sodium Alginate, Cross-linked Hyaluronic Acid, and/or Oxidized regenerated cellulose, for example. In various embodiments, a tissue thickness compensator can comprise a durometer in the 3-7 Shore A (30-50 Shore OO) ranges with a maximum stiffness of 15 Shore A (65 Shore OO), for example. In certain embodiments, a tissue thickness compensator can undergo 40% compression under 3 lbf load, 60% compression under 6 lbf load, and/or 80% compression under 20 lbf load, for example. In certain embodiments, one or more gasses, such as air, nitrogen, carbon dioxide, and/or oxygen, for example, can be bubbled through and/or contained within the tissue thickness compensator. In at least one embodiment, a tissue thickness compensator can comprise beads therein which comprise between approximately 50% and approximately 75% of the material stiffness comprising the tissue thickness compensator. 
     In various embodiments, a tissue thickness compensator can comprise hyaluronic acid, nutrients, fibrin, thrombin, platelet rich plasma, Sulfasalazine (Azulfidine®−5ASA+Sulfapyridine diazo bond))−prodrug−colonic bacterial (Azoreductase), Mesalamine (5ASA with different prodrug configurations for delayed release), Asacol® (5ASA+Eudragit-S coated−pH&gt;7 (coating dissolution)), Pentasa® (5ASA+ethylcellulose coated—time/pH dependent slow release), Mesasal® (5ASA+Eudragit-L coated−pH&gt;6), Olsalazine (5ASA+5ASA−colonic bacterial (Azoreductase)), Balsalazide (5ASA+4Aminobenzoyl-B-alanine)-colonic bacterial (Azoreductase)), Granulated mesalamine, Lialda (delay and SR formulation of mesalamine), HMPL-004 (herbal mixture that may inhibit TNF-alpha, interleukin-1 beta, and nuclear-kappa B activation), CCX282-B (oral chemokine receptor antagonist that interferes with trafficking of T lymphocytes into the intestinal mucosa), Rifaximin (nonabsorbable broad-spectrum antibiotic), Infliximab, murine chymieric (monoclonal antibody directed against TNF-alpha-approved for reducing signs/symptoms and maintaining clinical remission in adult/pediatric patients with moderate/severe luminal and fistulizing Crohn&#39;s disease who have had inadequate response to conventional therapy), Adalimumab, Total Human IgG1 (anti-TNF-alpha monoclonal antibody—approved for reducing signs/symptoms of Crohn&#39;s disease, and for the induction and maintenance of clinical remission in adult patients with moderate/severe active Crohn&#39;s disease with inadequate response to conventional therapies, or who become intolerant to Infliximab), Certolizumab pegoll, humanized anti-TNF FAB′ (monoclonal antibody fragment linked to polyethylene glycol—approved for reducing signs/symptoms of Crohn&#39;s disease and for the induction and maintenance of response in adult patients w/ moderate/severe disease with inadequate response to conventional therapies), Natalizumab, First non-TNF-alpha inhibitor (biologic compound approved for Crohn&#39;s disease), Humanized monoclonal IgG4 antibody (directed against alpha-4 integrin—FDA approved for inducing and maintaining clinical response and remission in patients with moderate/severe disease with evidence of inflammation and who have had inadequate response to or are unable to tolerate conventional Crohn&#39;s therapies and inhibitors of TNF-alpha), concomitant Immunomodulators potentially given with Infliximab, Azathioprine 6-Mercaptopurine (purine synthesis inhibitor—prodrug), Methotrexate (binds dihydrofolate reductase (DHFR) enzyme that participates in tetrahydrofolate synthesis, inhibits all purine synthesis), Allopurinol and Thioprine therapy, PPI, H2 for acid suppression to protect the healing line, C-Diff—Flagyl, Vancomycin (fecal translocation treatment; probiotics; repopulation of normal endoluminal flora), and/or Rifaximin (treatment of bacterial overgrowth (notably hepatic encephalopathy); not absorbed in GI tract with action on intraluminal bacteria), for example. 
     As described herein, a tissue thickness compensator can compensate for variations in the thickness of tissue that is captured within the staples ejected from a staple cartridge and/or contained within a staple line, for example. Stated another way, certain staples within a staple line can capture thick portions of the tissue while other staples within the staple line can capture thin portions of the tissue. In such circumstances, the tissue thickness compensator can assume different heights or thicknesses within the staples and apply a compressive force to the tissue captured within the staples regardless of whether the captured tissue is thick or thin. In various embodiments, a tissue thickness compensator can compensate for variations in the hardness of the tissue. For instance, certain staples within a staple line can capture highly compressible portions of the tissue while other staples within the staple line can capture portions of the tissue which are less compressible. In such circumstances, the tissue thickness compensator can be configured to assume a smaller height within the staples that have captured tissue having a lower compressibility, or higher hardness, and, correspondingly, a larger height within the staples that have captured tissue having a higher compressibility, or lower hardness, for example. In any event, a tissue thickness compensator, regardless of whether it compensates for variations in tissue thickness and/or variations in tissue hardness, for example, can be referred to as a ‘tissue compensator’ and/or as a ‘compensator’, for example. 
     The devices disclosed herein can be designed to be disposed of after a single use, or they can be designed to be used multiple times. In either case, however, the device can be reconditioned for reuse after at least one use. Reconditioning can include any combination of the steps of disassembly of the device, followed by cleaning or replacement of particular pieces, and subsequent reassembly. In particular, the device can be disassembled, and any number of the particular pieces or parts of the device can be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, the device can be reassembled for subsequent use either at a reconditioning facility, or by a surgical team immediately prior to a surgical procedure. Those skilled in the art will appreciate that reconditioning of a device can utilize a variety of techniques for disassembly, cleaning/replacement, and reassembly. Use of such techniques, and the resulting reconditioned device, are all within the scope of the present application. 
     Preferably, the invention described herein will be processed before surgery. First, a new or used instrument is obtained and if necessary cleaned. The instrument can then be sterilized. In one sterilization technique, the instrument is placed in a closed and sealed container, such as a plastic or TYVEK bag. The container and instrument are then placed in a field of radiation that can penetrate the container, such as gamma radiation, x-rays, or high-energy electrons. The radiation kills bacteria on the instrument and in the container. The sterilized instrument can then be stored in the sterile container. The sealed container keeps the instrument sterile until it is opened in the medical facility. 
     Any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated materials does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material. 
     While this invention has been described as having exemplary designs, the present invention may be further modified within the spirit and scope of the disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.