GB2113249A - Tissue cassette - Google Patents

Abstract

A tissue cassette (1) for use in the processing and/or storage of the tissues of organisms comprises a perforated base (2) bounded by an upstanding wall (3) and has means (4, 5) for engaging another such cassette for stacking. Such stacking may be accomplished base to open face and/or open face to open face. The latter arrangement doubles the storage capacity available for a sample. <IMAGE>

Description

SPECIFICATION Tissue cassette The present invention relates to a tissue cassette for use in processing and/or storage of the tissues of organisms.

Such cassettes are used in pathology to contain individual tissue samples during various processing operations and to serve as a base for an individual paraffin block in which a tissue sample or samples is/or embedded. These cassettes find particular application in toxicological and carcinogenicity studies in which pathology is used to evaluate and quantify the changes caused by test compounds on organs taken from laboratory animals on test. This involves the selection, fixation, trimming, processing and section cutting of tissue samples, A known example of such a cassette comprises a tray having a perforated base to which a removable perforated stainless steel lid is hinged.

The lid is provided to retain tissue in the cassette during processing. Such cassettes have a fixed capacity and are expensive to manufacture.

Furthermore, such cassettes require special racks into which they are individually placed to contain them during exposure to processing fluids and suitably fitted drawer or racks for subsequent storage.

According to the present invention there is provided a tissue cassette for use in the processing and/or storage of the tissues of organisms, said cassette comprising a perforated base bounded by an upstanding wall, and means for engaging another such cassette for stacking the latter upon the open face of the former.

In one embodiment, the cassette is adapted so as to engage the other in one of two orientations, namely, with the open face of this cassette directly adjacent either the open face or the base of the other. For this purpose, co-operating pegs and recesses are preferably provided on the top of the upstanding walls and on the bases of the cassettes.

The cassette may be made out of any material which is resistant to all the routine processing solutions with which it is to be employed. In a preferred embodiment, the cassette is moulded from a polymer resistant to all routine processing solutions An external side surface portion of the upstanding wall of the cassette is preferably provided with a flat matt surface allowing for example, either hot foil stamping or pencil mark identification of the individual cassettes.

In one embodiment of the invention, a recess is provided in the top surface of the upstanding waU of the cassette. This recess facilitates the free movement of fluid in and out of the cassette when another such cassette is stacked on its open face, yet is not sufficiently large as to allow the smallest of the tissue samples handled to escape the cassette.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings in which: Fig. 1 shows an embodiment of a tissue cassette of the present invention; Fig. 2 shows two such tissue cassettes arranged in open face to open face engagement with each other, and Fig. 3 shows a plurality of such tissue cassettes in stacked engagement.

A tissue cassette 1 comprising a substantially rectangular perforated base 2 bounded on all four sides by upstanding wall 3. Walls 3a provided on the shorter sides of the rectangular base are thicker than those walls 3b on the longer sides. As can be seen from Figure 1 a pair of pegs 4 and recesses 5 are provided on the top surface of the shorter walls 3a on diagonally opposite corners.

These pegs 4 and recesses 5 mate with corresponding recesses 5 and pegs 4 on the top surface of another identical cassette in the arrangement shown in Figure 2. Pegs 4 are also provided to mate with recesses 6 (see Fig. 2) provided on the corresponding diagonally opposite corners of the base of another tissue cassette 1 as in the arrangement of Figure 3.

One of the long side walls 3b is provided with a recess 7 which extends from its top surface. When two such cassettes 1 are arranged open faced to open face as shown in Figure 2 or stacked open face to base as shown in Figure 3, this recess 7 together with the perforated base 2 allow for the free flow of fluid through the cassette while retaining the smallest of the tissue samples handled within the cassette 1.

The external face of one of the short walls 3a is provided with a flat, matt surface for receiving either hot foil stamping or pencil mark identification for the cassette. In this embodiment, this face is inclined with respect to the cassette base 2 so as to be tilted upward to facilitate reading of the cassette identification marking.

As mentioned above, Figure 2 shows two tissue identical cassettes 1 arranged open faced to open face, pegs 4 of one cassette engaging recesses 5 of the other. This arrangement can be used for fixation or decalcification enabling large samples to be processed or several samples e.g. the femurs for many different animals, to be processed separately in a common solution container.

In Figure 3, the cassettes are shown stacked base to open face, pegs 4 of each cassette engaging the corresponding recess 6 in the base of the immediately adjacent cassette 1, one additional cassette being engaged open face to open face with the cassette at the top of this stack to act as a lid. A Barlok tier 8 is fixed securely round the stack to hold the cassettes in sequence and remains in place until processing is complete.

Prior to assembling the stack shown in Figure 3, the cassettes are numbered by a hot foil stamping machine or by pencil marking to identify the project number, animal number and block number and are arranged in order on the bench open face uppermost ready to receive trimmed tissues.

Appriopriate samples of each tissue are placed into the correct cassette according to the block code for that particular project, e.g. liver, kidney x 2 in cassette/block No. 1; heart, lung, spleen in cassette/block No. 2 and so on.

After checking that all tissue samples are present in the correct cassette the stack is assmebled and the Barlok tier 8 applied.

The stack can then be placed in a processing basket for immediate processing, post-fixation or decalcification.

When the stacks are removed from the tissue processer, they are placed in a reservoir of an embedding centre.

Each stack of cassettes is then removed in turn from the embedding centre reservoir and the Barlok tier removed. The cassettes are laid out open face uppermost to expose the processed tissue samples for subsequent embedding in paraffin wax.

The tissue sample is removed from each cassette in turn and orientated using heated forceps in a respective mould containing fresh molten paraffin wax so as to present the required sampling surface to the base of the mould. The base of the corresponding cassette is then placed in the top of the mould such that the molten wax penetrates through the perforations. Once the wax has solidified, the casette is embedded in the wax block containing the tissue sample which is then removed from the mould. Thus, the cassette acts as a permanently attached identification tag as well as a support for microtomy.

Embodiments of the present invention have the following advantages: 1. Since the cassettes can fulfil the dual purpose of a tissue receiving tray and a lid, on special lids need be processed or handled thereby reducing cost and simplifying the use of the cassette in the laboratory.

2. Since the cassette can be stacked, all tissues from one animal can be kept in a stack in a predefined order. In previous systems in which the cassettes were not stacked but kept in random order, the time consuming activity of sorting into numerical or animal order was required. Other systems require spirally fitted draws or racks for receiving the individual cassettes and mounting them in order which add to the cost and storage space required.

3. The stacking systems provided by the present cassette permit compact handling of tissue samples at all stages and minimizes the effort involved.

4. Coloured cassettes permit useful colour coding by sex, group, study, interim death or terminal kill etc.

5. Over and above the routine processing stages, cassettes can be used as a general purpose receptacle for tissues of suitable sizes for fixation, decalcination or post-fixation. By keeping tissues in one receptacle for these stages the transfer of tissues is avoided and tissue lost or damage is minimized.

6. The cassette of the present invention allows processing of small samples without wrapping.

Claims (8)

1. A tissue cassette for use in the processing and/or storage of the tissues of organisms, said cassette comprising a perforated base bounded by an upstanding wall, and means for engaging another such cassette for stacking the latter upon the open face of the former.

2. A cassette according to claim 1 said engaging means comprise a pair of upstanding pegs which extend from that surface of the upstanding wall remote from the base and a pair of co-operating recesses for receiving such pegs of another such cassette stacked thereon.

3. A cassette according to claim 2 wherein said pair of co-operating recesses are provided on the base of the cassette for receiving the peg of another such cassette stacked thereon, base to said open face.

4. A cassette according to claim 3 wherein a further pair of co-operating recesses are provided on said surface of the upstanding wall remote from the base to receive said pair of pegs of another such cassette stacked thereon, open face to open face.

5. A cassette according to claim 2, wherein the cassette is substantially rectangular in shape and the pegs are arranged diagonally opposite one another.

6. A cassette according to claim 1 wherein at least a portion of the external surface of said upstanding wall is matt for receiving identification markings.

7. A cassette according to any preceding claim, wherein a portion of that surface of the upstanding wall remote from the base is recessed to facilitate free movement of fluid into and out of the cassette when another such cassette is stacked on said open face.

8. A tissue cassette for use in the processing and/or storage of the tissues of organisms with reference to Figure 1 with or without reference to Figure 2 and/or Figure 3 of the accompanying drawings.