Abstract:
A tissue cassette for use during histological examination of tissue preferably comprises a receptale and a lid. The lid is preferably pivotally attached to the receptacle about a pivot axis. The cavity preferably has a maximum width measurable anywhere parallel to the pivot axis that is greater than its maximum length measurable in any plane perpendicular to the pivot axis. The lid preferably has a maximum width measurable anywhere parallel to the pivot axis that is greater than its length measurable in a plane that bisects the maximum width of the lid and is perpendicular to the pivot axis. The cassette, with its lid closed against the receptacle, preferably has a maximum width measurable anywhere parallel to the pivot axis that is less than the maximum length of the cassette measurable in any plane perpendicular to the pivot axis. Also, a method for using two histological specimen cassettes is disclosed.

Description:
TECHNICAL FIELD OF THE INVENTION  
       [0001]     The present invention pertains to the field of histological examination. More particularly, this invention pertains to cassettes for treating tissue samples in preparation of microscopic histological examination.  
       BACKGROUND OF THE INVENTION  
       [0002]     Cassettes of the type disclosed in U.S. Pat. No. 5,928,934 and 5,665,398, the disclosures of which are incorporated herein by reference in their entireties, are used to store, treat, and hold tissue samples in preparation of performing microscopic histological examination of such tissue. Typically, a cassette comprises a receptacle portion that forms a cavity and a lid. The receptacle and lid each typically have numerous small apertures that allow fluid to pass through the cassette and into the cavity. The lid is often attached to the receptacle by a hinge in a manner such that the lid can be used to selectively open and close the cavity of the receptacle.  
         [0003]     During the treatment of a tissue sample in preparation of microscopic examination, the tissue sample is typically placed in the cavity of a cassette with the lid of the cassette closed to prevent the tissue sample from inadvertently falling out of the cavity. The cassette is then typically immersed in sequence any number of various fluids such as formaldehyde, ethanol, xylene, and molten paraffin. The apertures in the receptacle and lid of the cassette allow such fluids to pass into the cavity of the cassette and make contact with the tissue sample. In the timing of these steps, a tissue sample is dehydrated, cleared and infiltrated with molten wax within the cassette. Multiple tissue samples in multiple cassettes can be treated in this manner simultaneously.  
         [0004]     The treatment procedures typically concludes with the tissue sample resting in molten paraffin. The lid of the cassette is thereafter opened and the tissue sample is removed from the cassette and placed in the cavity of an embedding mold. The cassette is then placed above the tissue sample in the embedding mold and additional paraffin is used to secure the tissue sample to the bottom surface of the cassette. This additional paraffin is allowed to solidify in and around the apertures of the receptacle and thereby provides a firm attachment of the tissue sample to the cassette. As such, the cassette can then be used to hold the wax infiltrated tissue sample as an investment casting of the tissue sample to be sliced by a microtome.  
       SUMMARY OF INVENTION  
       [0005]     The present invention is directed to an improved histological examination cassette. In one aspect of the invention, a histological specimen cassette is configured and adapted for use in connection with a larger specimen cassette that has an internal chamber that creates a parallelepiped void that typically has a length of at least 31.75 millimeters, a width of at least 25.4 millimeters, and a height of at least 5.08 millimeters. The histological specimen cassette comprises a receptacle and a lid. The receptacle has a bottom wall, opposite side walls, opposite front and back walls, and a cavity. The cavity is positioned between the sidewalls and between the front and back walls of the receptacle and is partially bound by the bottom wall. The bottom and top walls have a plurality of apertures that extend through the bottom and top walls and that create fluid passageways into the cavity. The lid also has a plurality of apertures that extend through the lid and that create additional fluid passageways into the cavity. The lid is movable between an opened position and a closed position relative to the receptacle. When the lid is in the closed position, the lid engages the receptacle and the cavity is partially contained by the lid. The histological specimen cassette is dimensioned such that the histological specimen cassette can fit entirely within the void of the larger specimen cassette when the lid is in the closed position.  
         [0006]     In another aspect of the invention, a histological examination specimen preparation cassette is disclosed. The histological examination specimen preparation cassette includes a receptacle and a lid. The receptacle has a bottom wall, opposite side walls, opposite front and back walls, and a cavity. The cavity is positioned between the sidewalls and between the front and back walls and is partially bound by the bottom wall. The bottom and top walls have a plurality of apertures that extend through the bottom and top walls and that create fluid passageways into the cavity. Similarly, the lid has a plurality of apertures that extend through the lid and that create additional fluid passageways into the cavity. The lid is pivotally attached to the receptacle generally about a pivot axis in a manner such that the lid is pivotable between an opened position and a closed position relative to the receptacle. When the lid is in the closed position, the lid engages the receptacle and the cavity is partially contained by the lid. The cavity has a maximum width measurable anywhere parallel to the pivot axis and a maximum length measurable in any plane perpendicular to the pivot axis. The maximum width of the cavity is greater than the maximum length of the cavity.  
         [0007]     In yet another aspect of the invention, a histological examination specimen preparation cassette is disclosed. The histological examination specimen preparation cassette includes a receptacle and a lid. The receptacle has a bottom wall, opposite side walls, opposite front and back walls, and a cavity. The cavity is positioned between the sidewalls and between the front and back walls and is partially bound by the bottom wall. The bottom and top walls have a plurality of apertures that extend through the bottom and top walls and that create fluid passageways into the cavity. Similarly, the lid has a plurality of apertures that extend through the lid and that create additional fluid passageways into the cavity. The lid is pivotally attached to the receptacle generally about a pivot axis in a manner such that the lid is pivotable between an opened position and a closed position relative to the receptacle. The pivot axis is oriented generally perpendicular to each of the side walls of the receptacle. When the lid is in the closed position, the lid engages the receptacle and the cavity is partially contained by the lid. The cassette has a maximum length measurable in any plane perpendicular to the pivot axis when the lid is in the closed position. This maximum length defines a lengthwise direction. The front wall is inclined relative to the bottom wall in a manner such that the front wall extends a lengthwise distance that is at least two tenths of the maximum length of the cassette.  
         [0008]     In yet another aspect of the present invention, an assembly is disclosed. The assembly includes a first histological specimen cassette having a receptacle and a lid, the receptacle having a bottom wall, opposite side walls, opposite front and back walls, and a cavity, the cavity being positioned between the sidewalls and between the front and back walls, the cavity being partially bound by the bottom wall, the bottom and top walls have a plurality of apertures that extend through the bottom and top walls and that create fluid passageways into the cavity, the lid having a plurality of apertures that extend through the lid and that create additional fluid passageways into the cavity, the lid being movable between an opened position and a closed position relative to the receptacle, the lid engaging the receptacle when the lid is in the closed position and the cavity being partially bound by the lid when the lid is in the closed position and a second histological specimen cassette that has an internal chamber that creates a parallelepiped void that has a length of at least 31.75 millimeters, a width of at least 25.4 millimeters, and a height of at least 5.08 millimeters wherein the first histological specimen cassette fits entirely within the void of the second histological specimen cassette when the lid is in the closed position to create the assembly.  
         [0009]     Still yet another aspect of the present invention is that a method for utilizing two histological specimen cassettes is disclosed. The method includes placing a first histological specimen cassette entirely within a void of the second histological specimen cassette for histological specimen examination, wherein the first histological specimen cassette comprises a receptacle and a lid, the receptacle having a bottom wall, opposite side walls, opposite front and back walls, and a cavity, the cavity being positioned between the sidewalls and between the front and back walls, the cavity being partially bound by the bottom wall, the bottom and top walls have a plurality of apertures that extend through the bottom and top walls and that create fluid passageways into the cavity, the lid having a plurality of apertures that extend through the lid and that create additional fluid passageways into the cavity, the lid being movable between an opened position and a closed position relative to the receptacle, the lid engaging the receptacle when the lid is in the closed position and the cavity being partially bound by the lid when the lid is in the closed position and the second histological specimen cassette that has an internal chamber that creates a parallelepiped void that has a length of at least 31.75 millimeters, a width of at least 25.4 millimeters, and a height of at least 5.08 millimeters.  
         [0010]     In another aspect of the present invention, a histological specimen cassette is disclosed. This histological specimen cassette includes a receptacle and a lid, the receptacle having a bottom wall, opposite side walls, opposite front and back walls, and a cavity, the cavity being positioned between the sidewalls and between the front and back walls, the cavity being partially bound by the bottom wall, the bottom and top walls have a plurality of apertures that extend through the bottom and top walls and that create fluid passageways into the cavity, the lid having a plurality of apertures that extend through the lid and that create additional fluid passageways into the cavity, the lid being movable between an opened position and a closed position relative to the receptacle, the lid engaging the receptacle when the lid is in the closed position and the cavity being partially bound by the lid when the lid is in the closed position, wherein the front wall slopes toward the bottom wall at an angle from about fifteen degrees to about twenty-three degrees from the bottom wall to create a writing surface to provide identification for the histological specimen cassette. This is for both the host (outer) cassette and the specimen containing inner cassette. The ability to write/label the identification on both the inner and outer cassette pair is essential to the chain of custody and positive identification (ID) for experimental and diagnostic protocol.  
         [0011]     These are merely some of the innumerable aspects of the present invention and should not be deemed an all-inclusive listing of the innumerable aspects associated with the present invention. These and other aspects will become apparent to those skilled in the art in light of the following disclosure and accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0012]     For a better understanding of the present invention, reference may be made to the accompanying drawings in which:  
         [0013]      FIG. 1  is a perspective view of the preferred embodiment of a histological examination specimen preparation cassette in accordance with the invention;  
         [0014]      FIG. 2  is a top plan view of the cassette shown in  FIG. 1 ;  
         [0015]      FIG. 3  is a bottom plan view of the cassette shown in  FIGS. 1 and 2 ;  
         [0016]      FIG. 4  is a front elevation view of the cassette shown in  FIGS. 1-3 ;  
         [0017]      FIG. 5  is a rear elevation view of the cassette shown in  FIGS. 1-4 ;  
         [0018]      FIG. 6  is a right-side elevation view of the cassette shown in  FIGS. 1-5 ; and  
         [0019]      FIG. 7  is a view of an assembly comprising the cassette shown in  FIGS. 1-6  positioned within the internal chamber of a prior art cassette. 
     
    
       [0020]     Reference characters in the written specification indicate corresponding items shown throughout the drawing figures.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as to obscure the present invention.  
         [0022]     The preferred embodiment of a histological examination specimen preparation cassette in accordance with the invention is shown by itself in  FIGS. 1-6 . The cassette  20  comprises a receptacle  22  and a lid  24 . The lid  24  and the receptacle  22  are preferably injection molded together out of polymeric material, which is preferably solvent resistant, as a single monolithic part in the configuration shown in  FIGS. 2-6 . The lid  24  is attached to the receptacle  22  via a thin bridge portion  26  that acts as a hinge and allows the lid and receptacle to pivot thereabout relative each other. However, the bridge portion  26  is configured and adapted to be frangible so that, if desired, the lid can be easily separated from the receptacle by ripping the bridge portion in half along the pivot axis.  
         [0023]     The receptacle  22  comprises opposite front  28  and back  30  walls, opposite side walls  32 , and a bottom wall  34 . The receptacle  22  also comprises a cavity  36  that extends down into the receptacle and that is partially bound by the bottom wall  38  of the receptacle. The cavity  36  is further bound by four intermediate walls  38  that slope from the bottom wall  34  to the top perimeter edge  40  of the cavity. Two of the cross directed intermediate walls  38  are generally perpendicular to the back wall  30  of the receptacle  22  and diverge from each other as they extend upward. These two intermediate walls  38  eventual merge into the side walls  32  adjacent the top perimeter edge  40  of the cavity  36 . The other two intermediate walls  38  are generally perpendicular to the side walls  32  of the receptacle  22  and also diverge from each other as they extend upward. One of these two intermediate walls  38  eventual merges into the back wall  30  adjacent the top perimeter edge  40  of the cavity  36 , and the other of these two intermediate walls eventual merges into the front wall  28  adjacent the top perimeter edge of the cavity  36 .  
         [0024]     The outer front wall  28  slopes toward to the back wall  30  as it extends upward and is preferably oriented between fifteen and twenty-three degrees from the bottom wall  34  of the receptacle  22 . More preferably, the front wall  28  is preferably oriented between sixteen and eighteen degrees from the bottom wall  34  of the receptacle  22 . More preferably still, the front wall  28  is preferably oriented seventeen degrees from the bottom wall  34  of the receptacle  22 . As such, the front wall  28  extends front to back more than two tenths of the front to back maximum length of the entire receptacle  22 . Each of the sidewalls  32 , the bottom wall  34 , and the intermediate walls  38  preferably comprises a plurality of apertures  42  to allow fluid to pass through such walls. Preferably the apertures  42  that extend through the bottom wall  34  are drafted in a manner such that the apertures increase in size as they tend from the exterior of the cassette into the cavity  36 . This increases the paraffin adhesion of a tissue specimen to the exterior of the cassette  20  by creating interlocking geometry between the cassette and the solidified paraffin. The front wall  28  is preferably devoid of apertures for permit identification (ID) labeling. A first larger rectangular opening  44  preferably extends through the rear intermediate wall  38  and the lower portion of the back wall  30 . A second rectangular opening  46  preferably extends down through the intersection of the front intermediate wall  38  and the front wall  30 . Each of the first and second openings is centrally positioned between the side walls  32 .  
         [0025]     The lid  24  of the cassette  20  preferably comprises a main rectangular portion  50 , a thumb release tab  52 , a rectangular ring protrusion  54 , a locking tab  56 , and an arcuate guiding and locking protrusion  58 . The main rectangular portion  50  of the lid  24  is preferably thin and planar and comprises a plurality of apertures  60  that extend therethrough. The thumb release tab  52  preferably extends from the front edge  64  of the main rectangular portion  50  in a coplanar manner adjacent one of the side edges  62  of the main rectangular portion. The rectangular ring protrusion  54  preferably extends downwardly (assuming the lid  24  is in its closed position as described below) from the main rectangular portion  50  in a direction generally perpendicular to the plane of the main rectangular portion. However, the rectangular ring also comprises a chamfer  65  that is angled in a manner such that the chamfer mates with the sloped intermediate walls  38  of the receptacle  22  when the lid  24  is closed. The locking tab  56  also extends downwardly from the main rectangular portion  50  adjacent the front edge  64  of the main rectangular portion and forms a locking tang  66 , which can also be referred to as a finger tab, that extends forward of the front edge. The locking tab  56  is preferably centrally positioned between the side edges  62  of the main rectangular portion  50 . The arcuate back guiding protrusion  58  preferably extends downward from the rectangular ring protrusion  54  and curves aft as it extends therefrom.  
         [0026]     As mentioned above, the lid  24  is able to pivot about the receptacle  22  by flexing the bridge portion  26 . Thus, the bridge portion  26  creates a pivot axis that is parallel to and aft of the back wall the receptacle  22 , and about which the lid  24  is able to pivot relative to the receptacle. When the lid  24  is in an open position relative to the receptacle  22 , such as shown in  FIGS. 2-6  or as shown in  FIG. 1 , the cavity  36  of the receptacle  22  is open from above. Alternatively, when the lid  24  is in a closed position relative to the receptacle  22 , such as shown in  FIG. 7 , the rectangular portion  50  of the lid covers the top of the cavity  36 . As the lid  24  is pivoted from an opened position to the closed position, the locking tab  56  of lid moves into the second opening  46  of the receptacle  22  where the locking tang  66  of the locking tab engages the front wall  28  of the receptacle and resiliently deflects the locking tab rearward until the locking tang reaches a position beneath the front wall. Thereafter, the locking tab  56  resiliently deflects back to its neutral position where the locking tang  66  engages against underside of the front wall  28  in a manner preventing the lid  24  from moving back to its opened position unless more than a threshold force is exerted between the lid and the receptacle  22 . Alternatively, the locking tang  66  of the locking tab  56  can be configured to extend rearward from the remainder of the locking tab and to lock beneath the intermediate wall  38  adjacent the front wall  28 .  
         [0027]     Additionally, as the lid  24  is pivoted from an opened position to the closed position, the guiding protrusion  58  of the lid moves into the first opening  44  of the receptacle  22 . If the bridge portion  26  is severed, the guiding protrusion  58  of the lid  24  can be inserted into the first opening  44  and used to create an alternative hinge connecting the lid to the receptacle  22 . In such a case, the guiding protrusion  58  of the lid  24  interlocks with the receptacle  22  and prevents the lid from separating from the receptacle when the lid is in its closed position. When the lid  24  is in the closed position, the rectangular ring protrusion  54  of the lid extends into the cavity  36  of the receptacle  22  where it prevents tissue samples from slipping out of the cavity between the lid and receptacle. Because the chamfer  65  of the rectangular ring protrusion  54  is sloped to match the slope of the intermediate walls  38  of the receptacle  22  a face-to-face seal is created that becomes tighter in a progressive manner as the lid  24  is closed.  
         [0028]     Moreover, when the lid  24  is in the closed position, the thumb release tab  52  extends above the front wall  28  of the receptacle  22  in a spaced apart manner. This allows a person to exert a prying force upward on the thumb release tab  52  while also pressing downward on the front wall  28  of the receptacle  22  in a manner overcoming the forward or rearward threshold force that otherwise prevents the lid  24  from moving back into an opened position.  
         [0029]     The lid  24  and receptacle  22  are dimensioned such that the entire cassette  20 , with its lid in the closed position, can be positioned within the cavity  80  of another larger cassette  82 , as shown in  FIG. 7 . More specifically, lid  24  and receptacle  22  are dimensioned to fit within a parallelepiped void having a length of 31.75 millimeters, a width of 25.4 millimeters, and a height of 5.08 millimeters. Furthermore, the distance between the side edges  62  of the rectangular portion  50  of the lid  24  is greater than the front to back length of the rectangular portion of the lid. Additionally, the side to side width of the cavity  36  of the receptacle  22  is greater than the front to back length of the cavity. However, the overall side to side width of the cassette  20  is less than the front to back length of the entire cassette.  
         [0030]     The above mentioned configuration the cassette  20  allows the cassette to serve the same purpose as a standard prior art cassette, without occupying as much physical space as such a prior art cassette. Additionally, the configuration the cassette  20  allows the cassette to be placed within the cavity of another prior art cassette in a manner such that the cassette can be used in tissue treatment devices that are specifically configured for prior art standard size cassettes.  
         [0031]     Furthermore, it should be understood that when introducing elements of the present invention in the claims or in the above description of the preferred embodiment of the invention, the terms “have,” “having,” “includes” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required.” Similarly, the term “portion” should be construed as meaning some or all of the item or element that it qualifies.  
         [0032]     Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art.  
         [0033]     Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims that follow.