Abstract:
An apparatus for holding a tissue sample including a retaining member having a first tissue engaging surface and at least one biasing element, the first tissue engaging surface being moveably attached to the retaining member by said biasing element; and a base having a second tissue engaging surface and configured to engage the retaining member to form an interior area with the first and second tissue engaging surfaces facing each other, wherein the at least one biasing element urges the first tissue engaging surface toward the second tissue engaging surface to retain the tissue sample therebetween in the interior area.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a Continuation application of U.S. application Ser. No. 14/204,375 filed Mar. 11, 2014, which claims priority from U.S. Provisional Application 61/798,728 filed Mar. 15, 2013. The entire disclosures of the prior applications are considered part of the disclosure of the accompanying continuation application, and are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present disclosure relates generally to a tissue cassette for retaining a tissue sample. 
       BACKGROUND 
       [0003]    A biopsy is the removal of a tissue sample to examine tissue for signs of cancer or other disorders. Tissue samples are obtained in a variety of ways using various medical procedures involving a variety of the sample collection devices. For example, biopsies may be open (surgically removing tissue) or percutaneous (e.g. by fine needle aspiration, core needle biopsy or vacuum assisted biopsy). 
         [0004]    After the tissue sample is collected, the tissue sample is analyzed at a lab (e.g. a pathology lab, biomedical lab, etc.) that is set up to perform the appropriate tests (such as histological analysis). Although this disclosure refers to a sample, it should be understood that the term sample can refer to one or more samples. 
         [0005]    In order to properly process the tissue sample a series of steps may be performed including:
       1. Grossing of the sample by cutting the sample to the proper size for analysis.   2. Fixing of the sample to immobilize molecular components and/or prevent degradation.   3. Embedding the sample in an embedding material, such as paraffin wax   4. Sectioning the embedded sample by using, for example, a microtome.       
 
         [0010]    In conventional methods, the grossing step involves a lab technician cutting the tissue to the appropriate size for analysis and then placing the tissue in a tissue cassette. During the fixation stage, the cassettes are generally exposed to a fixing agent or chemical (e.g., a solution of formaldehyde in water such as formalin) shortly after sample collection. For example, U.S. Pat. No. 7,156,814 discloses a cassette which can withstand tissue preparation procedures. 
         [0011]    After the tissue sample has been processed, the medical professional, in conventional methods, removes the tissue sample from the individual cassette to perform the embedding step. Specifically, the medical professional carefully orients the sample, based on the diagnostic view required, into a base mold containing an embedding material such as paraffin wax. Once the tissue is oriented properly in the base mold, the molten material is cooled to fully embed the tissue sample and hold it in the proper orientation. The paraffin is used to hold the sample in position while also providing a uniform consistency to further facilitate sectioning. While the term paraffin is used, this term is not limiting and describes an example of an embedding medium. 
         [0012]    Then the sample is removed and sliced into a plurality of thin sections (e.g., 2 to 25μ thick sections), often using a microtome, for further processing and inspection. Such sectioning of the sample often helps a medical professional properly assess the sample under a microscope (e.g. diagnose relationships between cells and other constituents of the sample, or perform other assessments). 
         [0013]    The current process requires human intervention at both the grossing and embedding steps. Such manual handling of the sample can increase the likelihood of mis-identifying the sample, cross contaminating the samples, or losing part or the entire sample. Additionally, the numerous steps of manual manipulation can often increase the time that it takes to provide a proper assessment for each sample, once the sample is collected. 
       SUMMARY OF THE INVENTION 
       [0014]    This invention provides a device that allows for the tissue sample to be orientated during the grossing step and to remain in the same orientation through all steps to the embedding step. Through the multiple embodiments, the tissue sample cassette of this invention reduces the manual handling of the tissue samples. Example embodiments of this application may address one or more of the above identified issues. However, an embodiment of this application need not solve, address, or otherwise improve on existing technologies. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is an exploded view of a tissue cassette according to a first embodiment in a non-assembled state; 
           [0016]      FIG. 2  shows an exterior sectional view the tissue cassette of  FIG. 1  in an assembled state; 
           [0017]      FIG. 3  shows an interior sectional view of the tissue cassette of  FIG. 1  in an assembled state; 
           [0018]      FIG. 4  shows a cut-out section of the biasing element on the tissue cassette of the above embodiment. 
           [0019]      FIGS. 5-6  show an alternate embodiment of the base. 
           [0020]      FIG. 7  is an exploded view of a tissue cassette according to another embodiment in a non-assembled state. 
           [0021]      FIG. 8  is an interior side view of a tissue cassette according to another embodiment in an assembled state with the tissue sample. 
           [0022]      FIGS. 9A-9B, 10A-10B and 11A-11B  show the tissue cassette according to alternative embodiments. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    In the following detailed description, reference will be made to the accompanying drawing(s), in which similar elements are designated with similar numerals. The aforementioned accompanying drawings show by way of illustration and not by way of limitation, specific example embodiments and implementations consistent with principles of an example embodiment. These implementations are described in sufficient detail to enable those skilled in the art to practice an example embodiment and it is to be understood that other implementations may be utilized and that structural changes and/or substitutions of various elements may be made without departing from the scope and spirit of an example embodiment. The following detailed description is, therefore, not to be construed in a limited sense. 
         [0024]      FIGS. 1-3  illustrate a tissue cassette  1  according to a first exemplary embodiment of the present application. The tissue cassette  1  retains a tissue sample  2  in the proper orientation to allow for the automation of the processing and a reduction in human error. 
         [0025]    A tissue cassette  1 , according to one embodiment of the invention, has a base  4  and a retaining member  6  which cooperate to retain the tissue sample  2 , as discussed below. In addition, a frame  8  may optionally be provided to surround the outer perimeter of the retaining member  6 . In this embodiment, the base  4  is connected to the frame  8  by latching member  9 , and the frame  8  is connected to the retaining member  6  by a locking member  12 . In this way, the retaining member  6  fits into the inside perimeter of the base  4  as shown in  FIGS. 2-3 . The base  4  may have a sealing member  10  which forms a liquid seal between the frame  8  and the base  4 . 
         [0026]      FIG. 3  shows the base  4  with a bottom surface which corresponds to a second tissue engaging surface  14 . The retaining member  6  is formed with a rim portion  16  and a tissue retaining element  18  having a bottom surface corresponding to a first tissue engaging surface  20 . Further, in a non-limiting embodiment, the retaining member  6  includes a biasing element  22 . 
         [0027]    In a non-limiting embodiment, the tissue retaining element  18  is attached to the rim portion  16  by the biasing element  22  and locking member  12 . The biasing element  22  urges the tissue retaining element  18  away from the rim portion  16 . The first tissue engaging surface  20  of the tissue retaining element  18  may be attached directly to the biasing element  22 . Alternatively, the first tissue engaging surface  20  of the tissue retaining element  18  may be connected to the biasing element  22  by a connecting portion  19 , which as shown in  FIG. 1 , may extend from the first tissue engaging surface  20  towards the rim portion  16 . 
         [0028]    Generally, when the base  4  and the retaining member  6  are engaged as shown in  FIG. 3 , an interior area  24  is defined between the base  4  and the retaining member  6  where the first tissue engaging surface  20  and the second tissue engaging surface  14  are facing each other. Prior to this engagement, a tissue sample  2  is placed into this interior area  24  in the desired orientation so that it rests on the second tissue engaging surface  14  of the base  4 . Upon engagement of the base  4  with the assembly of retaining member  6  to frame  8 , the biasing element  22  urges the first tissue engaging surface  20  of the tissue retaining element  18  towards the second tissue engaging surface  14  of the base  4  to firmly hold the tissue sample  2  in the chosen orientation between the first and second tissue engaging surfaces  14 ,  20  such that it can be held in position for processing and later be embedded with paraffin or the like. 
         [0029]    The biasing element  22  will now be described in additional detail. As noted above the tissue retaining element  18  is attached to the retaining member  6  by at least one biasing element  22 . In the illustrated embodiment in  FIG. 1 , the tissue cassette  1  has four biasing elements  22 , where two biasing elements are shown in the Figure on one wall and the other two are on the opposite wall. 
         [0030]    As shown in  FIG. 1 , each biasing element  22  is substantially hinged having an S or Z shape and attach at one end to the tissue retaining element  18  and attach at the other end to the inner surface of the rim portion  16 . The biasing element  22  urges the tissue retaining element  18  towards the base  4  to fix the tissue sample  2  between the first and second tissue engaging surfaces  14 ,  20 . Thus, the biasing element  22  can take on any shape that performs this function. For example, a torsion bar or a biasing element having another shape could also be used as discussed in more detail below. 
         [0031]    In one non-limiting embodiment, as shown in  FIG. 4 , each biasing element  22  may have a first member  26  with a first end  27  and a second end  29 . The first end  27  may be connected to the tissue retaining element  18 . Extending downward at an angle from the hinge or second end  29  of the first member  26  is a first angled member  28 . A second angled member  30  is connected to the first angled member  28  by a first curved hinged point  36 . The second angled member  30  extends upwardly from the first angled member  28  at an angle; and in a non-limiting embodiment, the second angled member  30  and the first angled member  28  form an angle less than 90°. Extending downwardly from the second angled member  30  is a third angled member  32 . The second angled member  30  and the third angled member  32  are connected by a second curved hinge point  38 . In a non-limiting embodiment, the third angled member  32  and the second angled member  30  form an angle less than 90°. Further, in a non-limiting embodiment, the third angled member  32  and the first angled member  28  form an angle less than 90°. A second member  34  connects to the third angled member  32  at a hinge point and extends substantially parallel to the tissue retaining element  18 . The second member  34  attaches to the rim portion  16  of the retaining member  6  in a non-limiting embodiment. 
         [0032]    The biasing element  22  has a particular flexibility to ensure that the tissue sample  2  is held between the first and second tissue engaging surfaces  14 ,  20 , on the one hand, but to also ensure that the tissue sample  2  withstands any permanent damage during processing. The preferred maximum biasing force depends on the tissue sample and is up to about 2.5N. Typically, biasing force may be measured using a force gauge. 
         [0033]    More detail with respect to the retaining member  6  will now be provided with reference to  FIGS. 1 and 2 . In this exemplary embodiment, the retaining member  6  includes the rim  16 , the biasing element  22 , the connector  19 , the retaining element  18  and the first tissue engaging surface  20 . The rim  16  has four walls and a substantially rectangular shape. On the inside of the rim  16  one end of the biasing member  22  is attached. One end of the biasing member  22  attaches to the tissue retaining element  18  at either the connector  19  or the first tissue engaging surface  20 . The tissue retaining element  18  of the retaining member  6  has a connector  19  and a first tissue engaging surface  20  with a substantially planar mesh portion  42 . In this embodiment the mesh portion  42  is rectangular in shape, but the shape is not limiting and the mesh portion can be a variety of shapes. The mesh portion  42  of the first tissue engaging surface  20  has a plurality of perforations  44  or cut-outs. When the mesh portion  42  is urged against the tissue sample  2  it holds the tissue sample  2  in place and allows reagents, or the like, to flow to the tissue sample  2  through the perforations  44  in the mesh portion  42 . The perforations  44  are sized to allow the flow of fluid to the tissue sample  2  on the one hand, but to prevent the escape of the tissue sample  2  on the other hand. Thus, the perforations  44  in the mesh portion  42  may be sized according to the size of the tissue sample  2 . Further, the first tissue engaging surface  20 , may alternatively be solid and have no holes on the surface while still allowing the agent to flow underneath the first tissue engaging surface  20  from the periphery. 
         [0034]    The first tissue engaging surface  20  of the tissue retaining element  18 , and/or the second tissue engaging surface  14  may contain topography to help orient the tissue sample. For example, the tissue engaging surfaces  14 ,  20  may contain prongs  45 , ridges, hooks, or the like as shown on a second tissue engaging surface  14  in  FIG. 5 . In certain non-limiting embodiments, the tissue retaining element  18  has a semi-rigid structure to secure the tissue sample  2  without deformation; however, the tissue retaining element  18  may also have a rigid structure without changing the scope of the invention. 
         [0035]    Further as shown in  FIG. 1 , the tissue retaining element  18  may also have protrusions  46  which extend downwardly from the tissue retaining element  18  towards the base  4 . The protrusions  46  act as dead stops to prevent the tissue retaining element  18  from pushing down too hard against the tissue sample  2 . 
         [0036]    Additionally, in a non-limiting embodiment, the retaining member  6  may have handles  48  which function as grips for the lab technician when transporting the tissue cassette  1 . Further, in a non-limiting embodiment, the retaining member  6  may contain a wire  47  which extends the length of the retaining member  6  and can be used for retraction when separating the retaining member  6  from the base  4 . 
         [0037]    The base  4  will now be described with reference to  FIG. 1 . As discussed above, the tissue cassette  1  has a base  4  which supports the tissue sample  2  and holds the paraffin for embedding. The base  4 , as shown in  FIG. 1 , has a generally rectangular shape with four side walls and a depressed bottom planar surface, referred to as the second tissue engaging surface  14 . The base  4  has a rectangular shape depicted in the Figures; however, it is not limited to this shape and a different shape could be used without changing the scope of the invention. The base  4  is preferably solid so that it can hold the paraffin for embedding. The walls of the base  4  are preferably tapered inward to improve the ease at which the base can be removed from the paraffin after the embedding process. 
         [0038]    As shown in  FIG. 1 , the base  4  has a solid, smooth bottom. However, in some embodiments the base  4  may have grooves or some other texture. As an example, the second tissue engaging surface  14  of the base  4  may have flow channels  43 , depicted in  FIG. 6 , to assist in retaining the tissue sample  2  and improving fluid flow, without changing the scope of the invention. In an alternative embodiment, the base  4  may be have a second depressed bottom for receiving the tissue sample such that the second depressed bottom creates an interior subsection with an area smaller than the interior area  24 . The second depressed bottom  49  may be used for tissue samples  2  smaller in size. 
         [0039]    In certain embodiments, the base  4  may also have drainage guides  50 . The drainage guides  50  help to wick away the paraffin and to channel the paraffin away from the tissue cassette  1  after the tissue sample  2  has been embedded. The drainage guides  50  extend out from the outer peripheral of the base. In the embodiment shown in  FIG. 6 , the drainage guides  50  extend from one of the two end walls of the base; however the drainage guides  50  could extend from any wall on the base  4 . 
         [0040]    As noted above, in some embodiments a frame  8  is placed around the outside perimeter of the retaining member  6  and functions to secure the retaining member  6  to the base  4 . The frame  8  may also be used as a means for identifying the tissue sample. As shown in  FIG. 1 , the frame  8  has a substantially rectangular shape with one end have an angled projection with an angled face  52 . As shown in  FIG. 1 , a label  54  may be placed on the angled face  52  to identify the tissue sample  2 . The labels  54  are described in more detail below. In this embodiment, the angle of the planar face is about 45 degrees, but the invention is not limited in this respect. The angled face  52  can be configured to receive a label such that the label  54  clicks into the angled face  52  of the frame  8 . Alternatively, the frame  8  may have a textured surface and be put through an inkjet printing system, such as Leica IPC ink jet printer. In this instance, the tissue cassette  1  can be assembled after printing or the base  4  along with the frame  8  can be configured to be sent through the printer. 
         [0041]    In a non-limiting embodiment, the frame  8  and the retaining member  6  are not easily removed so that once the tissue cassette  1  is used, the label  54  on the frame  8  will remain matched with the tissue sample  2  contained in the tissue cassette  1 . In certain embodiments, frame  8  has a locking projections  12  which projects from the inside the perimeter of the frame  8 , shown in  FIG. 1 . The locking projections  12  attach with an engaging portions  55  on the outer perimeter of the rim portion  16  on the retaining member  6  to secure the frame  8  to the retaining member  6 . Once the frame  8  is connected to the base  4  using this locking arrangement, it is difficult to separate them. 
         [0042]    The base  4  includes a latching member  9  which acts as a clip or lock to hold the base  4  to the frame  8 . Alternatively, if a frame  8  is not used, the latching member  9  can lock the base  4  to the retaining member  6 . 
         [0043]    As shown in  FIG. 2 , the latching member  9  is connected to a releasing member  60 . The latching member  9  is flexibly attached to the base  4 . When the latching member  9  is engaged, the latching member  9  attaches to the clip surfaces  56  on the outer perimeter of the frame  8 . The latching member  9  locks the base  4  to the frame  8  which is attached to the retaining member  6 . In this way, a sealing member  10  connects the latching member  9  to the base  4  to form a seal between the surfaces on the perimeter of the base  4  and the frame  8  to sufficiently prevent paraffin from leaking during embedding. In a non-limiting embodiment a gasket may be used as the sealing member  10  to help seal the base  4  and the frame  8 . The latching member  9  is disengaged by pressing downward on the releasing member  60 . When the releasing member  60  is pressed, the latching member  9  moves away from the base  4  and disengages from the clip surfaces  56 . In the embodiment described above, the sealing member  10  extends from the base  4 , but the sealing member  10  may also extend from the retaining member  6  or the frame  8 . 
         [0044]    An important aspect of tissue sample analysis is properly keeping track of tissue samples. In some embodiments, the tissue cassette  1  includes a label  54  or ID tag as shown in  FIG. 1 . The label can  54  be located anywhere on the tissue cassette  1 , but is preferably located on the frame  8 . In some embodiments, more than one tag may be present. When more than one tag is present, the tags can be physically separated or located together. 
         [0045]    The label  54  may be a computer or human readable tag including, but not limited to, labels having an incorporated RFID, labels having an incorporated one-dimensional barcode (1-D barcode), labels having an incorporated two-dimensional barcode (2-D barcode), and labels having an incorporated three-dimensional barcode (3-D barcode). However, the computer readable label is not limited to RFID, 1-D barcode, 2-D barcode, or 3-D barcode labels and may include any type of label readable by a computer as would be apparent to a person of ordinary skill in the art. 
         [0046]    In some embodiments, a label  54  is present that may be sensitive to changes to the sample or itself. For example, a label  54  may be present that changes physical (i.e. color) or chemical (i.e. redox, conjugation, etc.) properties during fixation of the sample. Similarly, a label  54  may be present that is sensitive to the processing steps which precede embedding (i.e. dehydration). Alternatively, a label  54  may be present that is sensitive to the embedding step (i.e. infiltration of paraffin). The label  54  may have a property that changes incrementally or switches when the step is complete. In this way, the technician, or an automated system, will be able to determine when the sample has finished one step before another is started. 
         [0047]    The tissue cassette  1  can be made from various materials and the same or different materials can be used for the retaining member  6 , including the tissue retaining element  18 , the first tissue engaging surface  20 , the mesh portion  42 , and the base  4 . Examples of materials used include: an acetal copolymer, Teflon, polypropylene, and stainless steel. In a non-limiting embodiment, the acetal copolymer is DELRIN 900. In a non-limiting embodiment, the base  4  is made out of a polypropylene material so that the base  4  does not attach to the paraffin after the tissue sample  2  is embedded. In a non-limiting embodiment, the sealing member  10  is made out of a polypropylene material. 
         [0048]    In a non-limiting embodiment, the tissue cassette, including the base, the retaining member, and/or the frame, may be produced from a material lacking any dye or coloring. The lack of color may allow the technician to view the tissue sample in the tissue cassette and ensure that the tissue sample has remained in its desired orientation after embedding. In these embodiments, the tissue cassette, including the base, the retaining member, and/or the frame may be at least at least opaque or clear. 
         [0049]      FIG. 7  shows a further embodiment of the tissue cassette  1 . This embodiment is different from the previously described embodiments in the following respects. First, instead of having a separate frame, the frame of this embodiment is integrally incorporated into the retaining member  6 . Second, the tissue retaining element  18  is shaped more like a basket, having four side walls. Lastly, the latching member  9  is formed on an end wall of the base  4 , but has the same function of locking the base  4  to the retaining member  6 . Other than these differences noted, the embodiment shown in  FIG. 7  has the same configuration and tracks the same structure as discussed above. 
         [0050]      FIG. 8  shows a further embodiment of the tissue cassette  1 . This embodiment is different from the previously described embodiments in that in this embodiment, a biasing member  58  may be provided on either the base  4  or the retaining member  6  or both, along with the biasing element  22  as described in the above embodiments. In this embodiment, the biasing member  58  on the retaining member  6  may be pushing down and the biasing member  58  attached to the base  4  may provide a biasing force to move the second tissue engaging surface  14  away from the first tissue engaging surface  20 . Furth, the biasing member  58  attached to the retaining member  6  may permit the retaining member  6  to move away from the base  4  in response to the biasing force provided by the base  4 . Similarly, the biasing member  58  attached to the base  4  may permit the base  4  to move away from the retaining member  6  in response to the biasing force provided by the retaining member  6 . In this embodiment, the tissue sample container  1  is stable when either the biasing member  58  attached to the retaining member  6  or biasing member  58  attached to the base  4  is applying a biasing force, or when both are applying or not a biasing force. 
         [0051]    For example, in this non-limiting embodiment, the biasing member  58  on the base  4  may be used only to enable the releasing of the force that is applied by the biasing member  58  on retaining member  6 . As an example, in this embodiment, the tissue cassette  1  provides a two position floor. The first position is when the biasing member  58  on the base  4  compresses the second tissue engaging surface  14  upwardly such that the tissue engaging surface is compressed up towards the retaining member  6  to compress the tissue sample  2 . The second position is when the force of the biasing member  58  on the base is released so that the second tissue engaging surface  14  is moves downwardly. In this way, the second tissue engaging surface  14  retracts away from the tissue  2 , such that the floor of the base retracts, similar to the first tissue engaging surface  20  of the previous embodiments retracting towards and away from the tissue sample  2 . Other than these differences noted, the embodiment shown in  FIG. 8  has the same configuration and tracks the same structure as discussed above. 
         [0052]      FIGS. 9-11  illustrate alternative embodiments of the invention which are directed towards maintaining parallel configuration of the first tissue engaging  20  surface when it urges towards the second tissue engaging  14  or when it retracts away from the second tissue engaging surface  14 .  FIGS. 9A and 9B  illustrate examples of guiding members  64  which assist the first tissue engaging surface  20  to maintain parallel configuration to the base  4  as it urges towards to the base  4 .  FIG. 9A  illustrates a wire guide  66  used as the guiding member. In  FIG. 9A  the wire guide  66  is attached to the retaining member  10 . The specific location is not limited; the wire guide  66  could be attached anywhere on the retaining member  10  including directly on the first tissue engaging surface  20 . In the example shown in  FIG. 9A , the wire guide  66  has a substantial U-shape with two parallel members  68  connected by a cross member  70 . Projections  72  extend out from one end of each of the parallel members  68  to attach to clips  74  in the center of the retaining element  18 . The wire guide  66  may pivot at the clips  74  such that when a downward force is applied to the wire guide  66  the retaining element  18  urges towards the tissue sample  2  along a central axis of the clips  74  to maintain a parallel configuration of the tissue retaining element  18  and the first tissue engaging surface  20  with the base  4 . The cross member  70  can be locked into place by cross member clips  76  attached to the frame  8  or the retaining member  10 . 
         [0053]      FIG. 9B  shows pillars  78  as guiding members  64 . In this embodiment, pillars  78  extend vertically upward from the interior of the frame  8 . Further, the side walls of the retaining member  6  have at least one cut-out  80  which are shaped to receive the pillars  78 . Accordingly, the retaining element  18  can maintain a parallel configuration with the base  4  when it moves towards the tissue sample  2  or away from the tissue sample  2 . 
         [0054]    In addition to the guiding members  64  discussed above, there are alternative designs relating to the biasing element  22  which help to maintain the parallel configuration of the first tissue engaging surface  20  to the base  4 . The biasing element  22  described above is one example of a means to hold the tissue sample  2  in the tissue cassette  1 . As noted above, any design that performs the function of urging the first tissue engaging surface  20  against the second tissue engaging surface  14  can be used. Alternate embodiments of the biasing element  22  to remain parallel configuration of the first tissue engaging surface  20  with the base  4  are shown in  FIGS. 10-11 . 
         [0055]      FIG. 10A  and  FIG. 10B  illustrate an alternate embodiment to the biasing element  22 . In these examples, the biasing element  22  includes two angled members. The first angled member  82  is fixed to the retaining member  6  at a fixed point  84  and angles downward from the fixed point  84  and attaches to the retaining element  18  at a first moving point  86 . The second angled member  90  attaches to the retaining member  6  at a sliding point  92 . The second angled member  90  is not fixed at the sliding point  92  and can slide against an inner ledge  93  of the retaining member  6  in a direction parallel to the second tissue engaging surface  14 . The second angled member  90  extends downward from the sliding point  92  and attaches to the retaining element  18  at a second moving point  94 . The first angled member  82  and the second angled member  90  are angled such that the members cross substantially in the center of each member at a hinge point  96 . 
         [0056]    In this embodiment, the first angled member  82  is fixed to the retaining member  6  at the fixed point  84 . The second angled member  90  is attached to the retaining member  6  at the sliding point  92 . Thus, the second angled member  90  can slide only in the direction parallel to the second tissue engaging surface  14 . Accordingly, as the first angled member  82  and the second angled member  90  urge the first tissue engaging surface  20  towards the tissue sample  2 , the first moving point  86  and the second moving point  94  move towards the tissue sample  2  while keeping the first tissue engaging surface  20  parallel to the base  4 , for example. 
         [0057]    In certain embodiments as shown in  FIG. 10A , the pair of angled members  82 ,  90  cross at the hinge point  96  and are connected by a torsion bar  98 . As shown in  FIG. 10A , the pair of angled members may be provided on each side of the tissue cassette  1 . Accordingly, the tissue cassette  1  has two pairs of angled members, although the number of pairs of angled members is not limiting. The two pairs of angled members are attached by a connecting bar  100 . The connecting bar  100  can connect the two pairs of angled members at any point along the members. 
         [0058]      FIG. 10B  shows an alternate embodiment, where the biasing element  22  is provided by a flexible hinges  102  at the connection points between the first and second angled member and the retaining element  18 . That is, there are flexible hinges  102  at the first moving point  86  or the second moving point  94 . Similar to the embodiment described in  10 A, the first tissue engaging surface  20  can maintain a parallel configuration to the base  4  while moving towards the tissue sample  2 . The flexible hinges  102  allow pair of angled members to flex under pressure. 
         [0059]    Alternatively, as shown in  FIGS. 11A and 11B , the biasing element  22  can comprise two angled members extending in a parallel direction. The first angled member  82  is attached to the retaining member  6  and the second angled member  90  is attached to the frame  8 . In  FIG. 11A , the frame  8  and the second angled member  90  are placed over the retaining member  6  and the first angled member  82  so that the first angled member  84  and the second angled member  90  are adjacent to each other and extend in parallel directions. 
         [0060]    The second angled member  90  contacts to the retaining member  6  at a hinge  104  and attaches to the frame a first pivot point  106 . The first angled member  82  attaches to the frame  8  at a second pivot point  108 . Accordingly, the retaining element  18  may be moved towards the tissue sample  2  in a parallel manner by the first angled member  82  pivoting about the second pivot point  108  and the second angled member  90  rotating about the first pivot point  106 . When the two angled member rotate about their respective pivot points the retaining element  18  moves in a substantially a parallel direction. Similar to the embodiment describe with respect to  FIGS. 11A and 11B , a torsion bar may be provided in this embodiment. The torsion bar may be located at any point where the two pair of angled members connect. 
         [0061]    An example of the use of the tissue cassette  1  in the analysis process will now be described. The tissue sample  2  is extracted and sent to a lab for analysis. In certain non-limiting embodiments, a gel may be placed on a tissue engaging surface, for example the second tissue engaging surface  14  as an adhesive to further secure the tissue sample  2 . An example of gel for use include agarose, agarose derivatives, modified agarose, low melt agarose, hydroxyethylagarose, low molecular weight agarose, agar, alginates, dextran, mannan, pectin, Ghatti gum and cellulose including hydroxypropylcellulose, histogel, hydrogel or combinations thereof, Then the tissue sample  2  is orientated and placed onto the second tissue engaging surface  14  of the base  4  of the tissue cassette  1 . The retaining member  6  is then placed over the base  4  and secured in place by the frame member  8 . Once the cassette is assembled, the biasing element  22  in the retaining member  6  is deflected to urge the tissue retaining element  18  of the retaining member  6  towards the tissue sample  2  such that the tissue sample  2  is held in its oriented position. 
         [0062]    The tissue cassette  1  is then processed and exposed to a molten substrate. In a non-limiting embodiment, the tissue cassette  1  is filled with paraffin. The molten paraffin infiltrates the tissue cassette  1  and enters the interior area  24  to embed the tissue sample  2  in its oriented position. The paraffin is then cooled such that it hardens at which point the tissue sample is embedded in a paraffin block and ready for sectioning. The base  2  is disengaged from the frame  8  such that the paraffin block including the tissue sample is exposed, resting on the first tissue engaging surface  20  of the retaining member. The paraffin block including the tissue sample can then be sectioned using a microtone. After the tissue sample  2  is sliced it is ready to be placed on a microscope slide for further processing and inspection. 
         [0063]    Although a few example embodiments have been shown and described, these example embodiments are provided to convey the subject matter described herein to people who are familiar with this field. It should be understood that the subject matter described herein may be embodied in various forms without being limited to the described example embodiments. The subject matter described herein can be practiced without those specifically defined or described matters or with other or different elements or matters not described. It will be appreciated by those familiar with this field that changes may be made in these example embodiments without departing from the subject matter described herein as defined in the appended claims and their equivalents. Further, any description of structural arrangement of components or relationship there between is merely for explanation purposes and should be used to limit an example embodiment. 
         [0064]    Aspects related to the example embodiment have been set forth in part in the description above, and in part should be apparent from the description, or may be learned by practice of embodiments of the application. Aspects of the example embodiment may be realized and attained using the elements and combinations of various elements and aspects particularly pointed out in the foregoing detailed description and the appended claims. It is to be understood that both the foregoing descriptions are an example and are explanatory only and are not intended to be limiting.