Method and structure for staining biologic slides

METHOD AND STRUCTURE FOR STAINING OF BIOLOGIC SLIDES

Background of the Invention

Field of the invention

Theinvention generally relates to microscopic examination of biologic specimens mounted on glass slides, and specifically involves the staining of such biologic specimens in preparation for microscopic examination. The staining and examining of biologic specimens occurs daily ו׳ in great numbers in hospital laboratories, emergency rooms, clinics, biology departments, blood banks, and many physi’־ clans’ offices, veterinarian offices’ and hospitals. The slides used are of glass and generally have a 1 x 3 face dimension, and a 1 mm. thickness. Some slides have a slightly 15 different face dimension of 25 ram x 75 mm or a different thickness of 1.2 mm. The specimens to be stained and examined may, for instance, be tissue, blood, sputum, or urine. The biologic specimens are usually smeared on the glass slide and left to air dry, often with heat or reagent 20 fixation.

The Prior Art

To stain a biologic specimen fixed on a glass slide, it is necessary ho bring a staining liquid or reagent into contact with the specimen on t^e slide. For the pre-׳ ־, sent purposes it will j^e understood boat the term staining includes application ^!,.ο the specimen cf any of various liquids or reagents during a staining process, even if a particular liquid dovs not itself produce the actual staining.

In one widely used prior art method of staining, n the slide is placed horizontally, specimen up, on a rack suspended in a sink. The staining !:.quid is pouted cr dripped from a bottle over the slide to flood the specimen. This technique wastes expensive staining liquid, since much more liquid is genetiilly squeezed or dripped than is actually ._כ needed f 0 :: staining. Also, the sink becomes stained '.nd unsightly after a period of time from the overflow liquid. The opera tor's fingers become stained when the specimen is picked up. When the bottle reagents remain in the sink area for a prolonged period of time, the fluid can deteriorate ;׳η or become contaminated, intentionally or accidentally.

It generally requires from 6 cc to 8 cc of each

I י י reagent :to perform a specific examination with the above ί technique.

A ?loss common alternative prior art method is ?3 to placo the slide or slides vertically in a rack, and then to dip ,the rack with the slide into a container of staining liquid.! This too uses an amount of dye far in excess of that actually necessary for staining, and, where the reagent is used for mace than one ־.־!ide, contamination often occurs. Likewise, this technique involves pouring liquid from bottles* into cc'.ntain׳»rs and pouring the staining liquid from con*<?;.net«.¹ into ׳?.i^ks.

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A third, again less common procedure is to use an automated staining device. Large hospitals with heavy workloads are more inclined to use this method. The machinery involved in such automated method is extremely expensive 5 and can only be justified where the amount of staining is extremely heavy. The cost of such machines prohibits their use in most staining operations. Furthermore, automated staining devices are only available for one or two stains.

. In one executional form of the invention, ^a slide with a specimen fixed thereon is inserted 10 vertically, lengthwise, into a confined chamber formed within a container. The slide is guided and positioned within the chamber on tracks. A thin film of staining liquid is formed on each face of the slide when the slide displaces a pool at the bottom of the chamber into confined 15 spaces adjacent to the faces of the slide. The volume of. staining liquid used, is approximately equivalent to the amount of liquid necessary to form the thin film on each face of the slide. This amount can be as little as 1 cc.

When sealed, the container is rendered tamperproof so that the contents cannot be adulterated prior to use, 25 thus preventing a false reading of the stained slide.

When the stained slide is vertically withdrawn from the chamber, the staining liquid drains ofg the slide and returns to a poo4, at the bottom of the chamber. The container and used liquid can then be disposed of. The 30 slide may be inserted and withdrawn from the chamber, and subsequently handled, by a portion of the slide which con״ tinuously extends above the chamber.

Substantially less staining liquid is required than in the prior art; a fresh batch of reagent is provided for each specimen? sinks are not stained since the liquid remains within the chamber? the operators* fingers do not become stained, since the staining liquid remains within the chamber; and, since the stain is prepackaged, the method is quicker and more time efficient.

The container is a disposable one intended for one use, and has a cover or stopper which seals the chamber and liquid until there is such use. The container is rendered tamperproof giving assurance that the staining process will yield a true result. After the staining is complete, the chamber may be easily resealed before disposal to avoid any subsequent spattering or leakage of stain from the chamber.

The above embodiment relates to a single slide, while the embodiment now to be described relates to simultaneously staining a multiplicity of slides.

The inventive concept of utilizing a thin film of staining liquid on each face of the slide, wherein the film is formed from a limited pool of staining liquid which is displaced by the immersion of the slide itself into the container, remains the same as in the first embodiment referred to above, but the present embodiment permits the ' basic concept to be used with a multiplicity of slides.

The present invention uses a holder that positions, spaces and secures slides with respect to one another. The spacing and positioning of the slides in the holder is critical to achieving the effect sought in the invention, namely a thin film on the face of each slide which is formed by the slides themselves in cooperation with the container when the slides are immersed into a limited pool which occupies only a portion of the container when the slides are not immersed therein. The slides, while spaced, positioned rind secured in the holder, are inserted into a special,

-צmatching, container holding a limited pool of staining liquid . The slides displace liquid of the pool, in the' fashion set forth in the parent application, so that a thin film is formed on the faces of the slides.

When the slides, by means of the holder, are withdrawn from the container, the films of staining fluid fall back into the container and reform substantially the same pool as originally formed.

The slides are then removed from the holder for further processing.

The holder, container, and pool are specifically designed for a designated number of slides, and it is intended that, in the preferred use of the system, no more and no less than the designated number of slides be used in and with that particular container, holder, and pool.

As with the single slide embodiment disclosed in the parent application, preferably the container is initially sealed with the staining fluid therein, and is resealed after use and before discard. The holder is, desirably, removably attached to the container prior to use, so that the elements of the invention are presented together for use in combination.

Of course, a cooperating container, holder, and staining liquid pool can be produced for any plurality of slides within reason, but it is contemplated that the most popular use will be a five-slide embodiment.

68384-2

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According to the invention.there is provided!;:' a container package for staining a plurality of specimens centrally arranged on the respective faces of a plurality of microscope slides, comprising (a) a slide holder for vertically supporting the slides at their upper ends to define a clamped assembly in which the downwardly extending portions at adjacent slides are in spaced parallel relation;

(b) a generally rectangular body member arranged with its longitudinal axis extending vertically and containing a generally rectangular upwardly-opening cavity for receiving the downwardly extending portions of the slides, the cavity having such a height less than the length of the slides as to cause the upper ends of the slides in said assembly to extend above said body member and the specimens to be completely disposed within the cavity when the downwardly extending portions of the slides are fully inserted in the cavity;

(c) guide means arranged in the corners of the cavity for maintaining a spaced relationship betwen the opposed outer end faces of the inserted slides and the cavity walls;

and (d) a quantity of staining liquid partially filling the cavity, the depth of said staining liquid prior to insertion of the slides in the cavity being less than the distance between the specimens and the inserted ends of the respective slides;

(e) the slides being supported in sufficiently close relation, and the walls of said cavity conforming sufficiently close to the lower perimeters of the slides, that when the lower portions of the slides are inserted into the bottom of the cavity, the staining liquid rises to a level sufficient to cover the specimens on the respective slides with a thin film of said staining liquid.

Brief Description of the Drawings

Fig. 1 is a perspective view of a slide staining device.

Fig. 2 is a perspective view of a conventional glass slide of either metric or English dimensions.

Fig. 3 is a perspective view similar to Fig. 1 showing the slide staining device with the cover removed and a slide inserted.

Fig. 4 is a view of a conventional slide such as shown in Fig. 2, having been stained in the device of Fig. 1.

Figs. 5 through 8 are sectional elevational views showing a slide in successive stages of its insertion into the device of Fig. 1 of the invention.

iO Fig, 9 is a graph illustrating a principle involved in the steps of Figs. 5 through 8.

Fig. 10 is an enlarged sectional elevational view taken on the line 10-10 of Fig. 1, showing in greater detail the interior design of the staining device of Fig. 1.

Fig. 11 is a transverse sectional view taken on the line 11-11 of Fig. 10, showing still further details of construction.

Fig. 12 is a plan view of the staining device directly beneath the foil cover taken on the line 12-12 20 of Fig. 10, showing details of the slide entrance aperture on the upper face of the staining device.

Fig. 13 is a sectional plan view taken on the line 13-13 of Fig. 10, showing the profile and proportions of the interior chamber and slide-guiding slots of the stain25 ing device.

Fig. 14 is an enlarged sr 'onai elevational view similar to Fig. 10, but showing a. slide fully inserted in the staining device, such as is shown in Fig. 3, and showing the combined proportions and the positions of the slide 3¢ and slide-staining device in use.

-ΊFig. 15 is a transverse sectional elevational view taken on the line 15-15 of Fig. 14 showing central positioning of a slide carried in slots and showing liquid displacement chambers formed on the front and rear faces 5 of the slide.

Fig. 16 is a sectional plan view taken on the line 16-16 of Fig. 14, showing relative proportions and positions of the slide and slide-staining device, and liquid displacement chambers formed on the front and rear sides 10 of the slide.

Fig. 17 is a perspective view of the multiple slide staining tank of this invention, with the seal cover partially removed.

< Fig. 18 is an exploded perspective view showing both the slide holder and staining tank of the invention.

Fig. 19 is a perspective view of both the slide holder and staining tank, in a co-acting condition in accordance with this invention.

Fig. 20 is a perspective view of the empty slide holder of this invention prior to loading.

Fig. 21 is an exploded perspective view of the slide holder shown in Fig. 20 showing all the co-acting elements of the slide holder of this Invention. /

Fig. 22 is a perspective view of the slide holder of Figs. 20 and 21 being loaded with five slides to be stained. Fig, 23 is a sectional elevational view taken on the line 23-23 of Fig. 22, showing the five slides loaded in the holder, prior to clamping therein.

Fig, 24 is a sectional plan view taken on the 30 line 24-24 of Fig, 23 showing additional details of the five loaded slides loosely held by the slide holder.

Fig. 25 is a sectional elevational view similar to Fig. 23 but showing the five slides clamped in tightly held spaced relationships, and with the five slides extending in planes normal to the top and bottom faces of the slide holder.

Fig. 26 is a view similar to Fig. 24, but showing the slides in a clamped position.

Fig. 27 is a side sectional elevational view of the slide staining tank taken on the line 2727־ of Fig. LQ : 17, . showing interior details of the tank.

Fig. 28 is a front sectional elevational view of the slide staining tank taken on the line 28-28 of Fig. 17, showing additional details of the tank interior.

Fig. 29 is a side sectional elevational view taken _l5 on the line 29-29 of Fig. 19, showing details of the tank interior when in engagement with the loaded slide holder.

Fig. 30 is a front sectional elevational view taken on the line 30-30 of Fig. 29, showing additional details of the tank interior when engaged with the loaded slide 20 holder and showing the resultant upward displacement of a staining fluid about the slides.

Description of the Preferred Embodiments

A conventional slide 20 is shown particularly in Figs. 2 and 4. The slide 20 is simply a rectangular 25 piece of glass 21 on which a specimen 22 is mounted for microscopic examination. The slide has opposed flat surfaces or faces 23 and 25, Opposed long edges 26 and 27, and opposed short edges :.J.

The most commonly used slide has a length (Lg) 30 of approximately 3, a width (W_g) of approximately 1, and a thickness (Tg) of approxim״Lely lititn. In some instances, the slide may have a of 75mm and Wg of 25mm, or a Tg of 1.2mm.

These dimensions may vary slightly with different manufacturers. For instance, thicknesses may vary from .0525 to .0325, and the width may vary from 1.016 to .964”.

The specimen 22 is prepared and then affixed to a face of the slide in any well known manner such as by ' use of air drying, heat, or reagent.fixation. The specimen 22 is generally positioned at the center of one of the slide faces, with a clear zone, free of the specimen, on each end of the face. The specimen is virtually invisible at this point, prior to staining.

The slide 20, with the unstained specimen 22 thereon, is intended to be inserted into a disposable slide-staining device 30. Device 30 is desirably formed of a transparent 15 or translucent plastic into a generally long rectangular configuration having proportions generally conforming to the proportion of the slide 20. The device is intended to be used vertically, and has a top 31, a bottom 32, edges 33 and sides 35 and 36. A collar or flange 29 surrounds top 30 and has a flat surface thereon.

An internal cavity or chamber 40, likewise is rectangular in configuration and again, conforms generally to the proportions of the slide 20. The internal cavity 40 has opposed tapered vertical tracks 41 and 42, along 25 the vertical edges 43 and 45 of the cavity extending from the top 40 of the cavity to the bottom 47. The cavity also has opposed sides 48 and 50.

The cavity 40 has at its upper end a sloping, downwardly converging portion 51 having beveled edges 52 30 and sides 53.

A cover or seal 55 is affixed to the top 31 on collar or flange 29 by suitable means, such as heat sealing or adhesive. The cover is intended to be peeled back by grasping and pulling on tab 56 prior to use, so that the cavity 40 is exposed.

A pool of staining liquid 60 is contained within the cavity and extends about halfway up the cavity, as seen in Figs. 1 and 10.

The device is intended to be manufactured at a central facility whereat it is sealed with the staining liquid therein, as seen in Fig. 1.

As seen in Figs. 5 through 8, there is shown in sequence views of a slide 20 being inserted into the cavity 40. In Fig. 5, the slide 40 with a biological specimen !5 22 to be stained affixed thereon, is shown entering the cavity 40 on tracks 41 and 42. The slide 20 is spaced from the opposing sides 48 and 49 as seen best in. Figs. 15 and 1,6. The slide in Fig. 5 is just about to contact the upper surface of the pool 60, which is the static liquid level.

The static liquid level is ,at a heighth of above the bottom of the cavity.

In Figs. 6 and 7, the slide progressively descends into the cavity below the pool, the liquid in the pool is displaced and rises until the dynamic fluid level reaches 25 ^h2. as seen in Fig. 8, when the slide is fully inserted.

• At this point, the staining liquid entirely covers specimen 22. Ik is approximately one-half of Hj. H2 also represents the heighth of the cavity as seen best in Fig. 14.

Τ ' j_n Fig. 9, the principle described and shown in

Figs. 5 through 8 is illustrated, in graph form. As the slide is submerged below the static liquid level, there is a corresponding rise in the dynamic liquid level of the . staining liquid in virtually a straight line relationship.

״11As the slide is removed from the staining liquid, <ifter being left therein for an adequate period to accomplish staining, the slide is withdrawn and the reverse sequence occurs. The liquid level falls correspondingly as the liquid 5 drains from the side of the slide into the pool. There is some residual staining liquid that adheres to the specimen and the slide, and of course the pool heighth at the end of staining drops correspondingly below the static liquid level, when the slide is withdrawn from the device. The 10 slide when withdrawn from the device 30 has thereon the stained specimen 54 as seen in Fig. 4. Since the device is intended for a one-time use, such drop in the pool heighth and volume is not objectionable.

The tapered or guide portion 51 with beveled edges 152 .1־ and beveled side 53 permits easy insertion of the slide into the tracks’. It also acts as a well to catch any overflow of the staining liquid, including any splashing where the slide is dropped rapidly into the cavity. A collar or guide portion 29 extends around the upper end or top _2l; of the device and is integral therewith. Flange 29 has desirably a flat top portion 63 which permits a foil or cover.55 to be suitably secured thereto as by adhesive, or by a suitable heat-sealing technique. The foil can be of a metallic or a plastic material capable of being peeled 25 back from the covering by grasping a tab portion 56 and pulling to a completely open position, as seen in Fig. 3. The cap portion in sealing and covering position is shown in Figs. 10 and 11.

There is variability in the width and thickness 30 of slides, even those claiming to have specific dimensions. By tapering the tracks, the device will receive a slide cf variable thickness and variable width and still keep rhe slide away from the inside wall of the cavity. Additionally, the tapered tracks assure that only the edge of V. ׳he slide will touch the track and not the surface which 1׳jntainr> the specimen.

The slide 20 when inserted into the cavity 40 on the tracks 41 and 42 assumes a very definite position and posture within the cavity and with respect to the sides or walls 48 and 49 of the cavity 40.

As seen in Figs. 14 to 16 inclusive, the slide when inserted into its bottommost position has a top portion 61 which extends above the cavity 40 and top 31 of the device 30. The top portion 61 of the slide 20 is clear of any specimen 22, since the specimen zone is conven10 tionally in the middle of the slide as shown in Fig. 14 by phantom lines. The portion 61 of the slide 20 remaining above the device 30 is used to grasp the slide for inserting into the device and for withdrawing the slide from the device. The slide is also grasped by this portion during the rinsing 15 subsequent to the staining. In this way, the operator's fingers remain free of contact with the staining solution, and free of the dye. Approximately one-sixth of the length of the slide I>_s extends above the device 30.

The specimen 22 is stained when the slide is fully --סי inserted as shown particularly in Figs. 14 through 16 inclusive. The slide as seen particularly in Figs. 15 and !ס is positioned centrally of the cavity 40 and spaced from walls or sides 48 and 49. The slide 20 has adjacent to each face thereof spaces 65 and 66 which contain staining 25 liquid. The slide can be inserted with the specimen 22 facing in either direction as the slide 20 enters the cavity. The face of the slide 20 and the specimen 22 thereon is positioned so that the specimen 22 cannot contact the sides of the cavity, but rather the specimen is held in a way 30 that exposes it to the staining liquid in the space 65 or 66 formed by the slide and the side of the cavity. A minimum amount of staining liquid is necessary to stain the specimen when the slide is so positioned. This is clearly shown in the sectional views in Figs. 15 and 16.

It will be seen from the above description that the space 65 and 66 adjacent to each face of the slide when the slide is fully inserted into the cavity is a flat thin space which contains a suitable amount of staining liquid 5 to properly stain the specimen thereon, without excess use of such liquid. Furthermore, the slide itself is used to position this liquid adjacent to the faces of the slide, and the specimen on one of the faces. It will be seen that it does not matter as to which direction the specimen faces 10 when inserted into the cavity, since there is film on both !.aces of the slide.

The slide itself, in cooperation with the container, creates the film adjacent to the slide faces for staining, and then permits the liquid in those spaces to drain back 15 into the bottom of the cavity and pool formed therein when the slide is removed.

In Figs. 10 through 16 inclusive, there is shown in detail the interior of the device of Fig. 1. _Wg is the width of the slide 20, L_g is its length, and T_g is its thickness. h₂, which is the heighth of the cavity, as well as the heighth of the dynamic liquid level discussed above, is approximately three-quarters of the slide length L The tracks 41 and 43 comprise tapered walls in the edges of the cavity, as shown. The width between the 25 tracks, W_T, _as seen in Fig. 13, is slightly greater, for instance, .02 greater, than the width of the slide W , so that there is adequate clearance for the slide to move in the tracks. T_?, the thickness of the track at its tapered end, is slightly less, for instance, .016 less, than the thickness of the slide T_g. y, the thickness of the cavity, is approximately twice the slide thickness, T By virtue of the tapered tracks 41 and 42, the slide, when inserted in the tracks, is centrally spaced between the side walls of the cavity, 48 and 49. Where the thickness of the cavity is twice that of the slide, the thickness of the spaces formed on each face c|f the slide when the slide is inserted will be approximately one-half the thickness of the slide.

By virtue of the tapered tracks 41 and 42, slides with slightly varying dimensions as set forth above will be suitably spaced within cavity 40. The tapered walls of the tracks 41 and '42 will compensate for these slight variations by guiding; the slide at its edges thereof while still positioning the slide. Even with a slide having the smallest width and/or:thickness within the variable dimensions, the slide is shill spaced from the sides of the cavity, although all edges ofthe slide may not be in firm contact with the tracks. Even though such a relatively small slide may have more freedom to move about within the cavity than a relatively large slide, the restraint imposed on the corners of the slide by the tapered walls of the tracks keeps the slide spaced from the cavity walls so that a film of staining fluid can be formed adjacent the slide faces.

It should be understood that the dimensions given above are merely illustrative to indicate a suitable dimensioned container to practice the invention.

Referring no?* to the preferred embodiment of the invention for simultaneously staining a multiplicity of slides; and with particular reference to Figs. 17-30, slides 120 are of the nature, size and design described above with respect to slide 20.

The container 130 may be generally similar to the container 30 described above, in shape, heighth, and width, except the horizontal depth of the container is extended to receive a plurality of slides, rather than only one, as will be described. The container 130 has an open top 131, a bottom 132, edges 133, 134, sides 135, and 136, and collar or flange 129.

The internal cavity or main chamber 140 of con.| tainer 130, has four tracks such as 3^41 and 142 in its four vertical corners, vertical edges 143 and 145, a bottom 147, and opposed sides 148 and 150.

In the version shown, the main chamber has at its top an overflow chamber 160 formed in the flange portion 129 which has side walls 168,170 formed by sides of the main chamber 140, end walls 172,174 and bottom ledges such as 180.

A seal cover 186, similar to seal 55 described above, is affixed to top 131 of the container.

The slides <Ue spaced, positioned, and securely held in holder 200, which consists essentially of a drawer 202, a case 204, and spacers such as 206. The spacers are slidably and pivotally suspended in case 204 on pivot trunnion pins such as 210 which ride in tracks 212 and 214 on the interiors of the opposed sidewalls 215,216 of the case. Drawer 202 slides into case 204 so that when moved ihwardly it pushes against at least the foremost spacer 217.

The case 204 has a closed top wall 218 and an open bottom. (The case is shown inverted, in the loading ¹ position, in Figs. 20, 21, 22, 23 and 25.) The side walls 215,216 contain respective slots 224 and 226, an open front and a closed back wall 230.

The tracks 212 and 214 in the case 204 are each formed by parallel ridges which define channels 232, 234 for receiving the pins 210 on the spacers.

The spacers are thin, flat rectangles which preferably have, at their long edges nearest the pins, a tapered edge or point for facilitating insertion between them of one end of the slides. The pins are near the edges of the spacers so the spacers hang free and loose in the tracks before loading of the slides. Preferably, these spacers are ail alike.

The drawer_? 202 has a front wall 300, push and pull knobs or ears 302, 304 at the opposite sides of the front wall, sides 3C6,308_r and diagonal interior braces 310, 312 extending between the front wall and the side walls of the drawer. Th״ side walls 306,308 each have a cam tooth such as 314 intended to ride in a corresponding slot such as 226 in the side wall of the case when the drawer is inserted into the case. The drawer side walls fit inside of, and in sliding engagement with, the case side walls. Each of the cam teeth 314 has a sloping surface such as 320 which permits the drawer to be inserted into the case until the teeth engace in their corresponding slots 224 and 226, after which the klat end surface 322 on the tooth prevents the drawer from unintentionally being pulled all the way out of the case.

The drawer is desirably made of a relatively flexible plastic material such as polyethylene, wherein there is a degree of give, particularly to the sides beyond the braces, for purposes which will be explained later. The spacers are likewise desirably made of such flexible material. In contrast to the drawer and spacers, the case is made of a relatively rigid material such as glass-filled ;nyl on, so that the relatively flexible drawer and spacers, in combination with the relatively rigid case, will permit the drawer to lock the spacers to the case as described hereinafter. !

It is intended that container 130 contain a confined or limited pool □f staining fluid 360. As best seen in Figures 27 and 28, this pool extends to a height H, which is preferably somewhat over one-half of the height of the chamber 140, ״17As with th* single slide embodiment shown in Figs.

through 16, it is Intended that slides 120 be inserted downwardly into this pool 360, whereby staining liquid of the pool will be displaced upwardly in the main chamber substantially to the top thereof without overflowing into the overflow chamber, but in the event of excess upward flow of displaced liquid this may be^- caught in the overflow chamber 160. If. a preferred design, the proportion of parts and depth of pool are such that no substantial overflow occurs, and ;in such case the large overflow chamber can be eliminated and. the top of the container made as in the single-slide version of Figs. 1-46.

The slides are held in exact spaced relationship with each other and the container so that a thin film is formed on both sides of the slides. The space between the slides conforms to the thickness of the spacers. Desirably, this thickness is approximately equal to the thickness of the slides themselves, which as indicated above can be about 1 mm. The spacing is such that when the spaced slides are secured in the holder, and the slides are immersed in the limited pool in the container substantially to the bottom thereof, the pool will be displaced so that the staining liquid rises in thin films which reach and cover substan״ tially all the slide portion which extends into main chamber of the container, and particularly the portions to which the specimens are affixed.

The positioning and spacing of the slides are accomplished in the holder, which initially is placed on its top, in an inverted position. The spacers are allowed to hang freely on their trunnion pins in tracks 212,214 as seen in Figs. 22, 23 and 24. At this time, the drawer 202 is open, and side walls 306 and 308 of the drawer are parallel and in a relaxeji position, whereby the drawer can slide freely in the case, Except that the drawer cannot be withdrawn completely out because of the interfering action of cam teeth 314.

As shown in Fig. 22, slides 120 are then inserted between the spacers such as 206, with the beveled edges of the spacers aiding entry of the slides between the spacers. The spacers and slides are preferably of the same width. The width of the cas׳> between its side walls is equal to the width of the slides plus a slight clearance dimension. During assembly, the slides are dropped to the bottom of the inverted case!, so that the straight edges of the ends of the slides rest on the interior of the top wall of the case. When the necessary number of slides has been inserted in the holder, which is five for the five-slide holder and container¹ embodiment shown, the drawer is pushed closed from the position shown in Figs. 23 and 24 to the position shown in Figs. 25 and 26.

Sidewalls 306 and 308 of drawer 202 terminate at their free ends in respective wedges 370, 372 having respective, confronting, tapered wedging surfaces 374,376 adapted to enter the above-mentioned clearances between spacers and side walls when the drawer is closed. Also, when the drawer is closed, the outer ends of sidewalls 306 and 308 are spread outward due to the wedging actions of surfaces 374, 376 against the ends of the spacers. The wedges are formed in the side walls beyond the braces 310, 312, so that the side walls are held relatively parallel up to the end of the braces, while the remaining outer end portions of the side walls are relatively free to flex outward under the influence of the spacers, and against the inside of the side walls of the case. The resistance of the spacers and slides against, the wedges therefore serves to jam the wedges against the side walls of the drawer, so that the drawer, the slides and the spacers are locked in position, with the slides clamped between the spacers. The spacers, which are relatively flexible, give slightly against the hard glass of the slides and then serve to cushion-grip the slides,. The slides are now held parallel to one another, and evenly spaced from each other by predetermined distances.

If there is any slight misalignment of the slides because the ends of the slides are not touching the interior of the case top, or because the slide ends are not entirely square with the slide s-.des, any such slight misalignment can be remedied by forcing the slides into the correct position manually, with one's fingers.

The outside dimensions of the five-slide group extending from the holder closely conform to the chamber designed for the five-slide staining operations. These dimensions are such that when the holder is inverted from the loading position and the exposed portions of the slides inserted into the container, the edges of the outside slides touch the sides of the tracks such as 141,142 in the container, whereby, when the slides, by means of the holder, <re inserted into the container, there is formed a thin space adjacent to each of the outside faces of the outside slides. The tracks such as 141,142 can be molded integrally with the remainder of the container, and may have lead-in bevels at their entrance ends to facilitate insertion of the slide assembly.

As the slides are immersed into the pool, the liquid is displaced upwardly along the slide faces. The dimension of the portion of the slides extending into the holder is preferably such that when the holder comeis into contact with the top of the container, the slides almost touch, or are just slightly above, the bottom of the con־ tainer. Thus, essentially all of the staining liquid at this time extends in thin films across the faces of the slides, and across the*specimens on the slides. The liquid rises to the top of the chamber, and permissibly into the overflow chamber if one or more of the slides is slightly thicker than a generally standard slide.

When the specimens have been thus stained, the slides are withdrawn f::om the container by means of the holder. The staining fluid drains off the slides, back into a pool of approximately the same size as the beginning pool minus the quantity which adheres to the slide. The container can permissibly be resealed with the original seal, and then neatly discarded. The holder and slides are then inverted and the slides unloaded from the holder in essentially a reverse operation from the loading operation described above.

In order to withdraw the drawer from the case and to release the grip of the spacers on the slides, it is necessary to break the wedging action of the sides of the drawer. To do this, the drawer is gripped at its ears 302 and 304 between the fingers, and an alternating rocking motion is exerted on the drawer as the drawer is withdrawn from the case, which is anchored by the fingers of the operator’s other hand. The case is desirably resting on a table during the unloading operation. After the jamming and wedging action of the drawer is thus broken, the drawer is withdrawn to release the spacers and slides to the position shown in Figs. 23 and 24. The slides can then be delicately removed from the holder and further processed by rinsing and the like, in the usueil way.

The holder can optionally be washed and rinsed and then used with a new container and pool, or the holder =can be thrown away.

It is intended that the container and holder be mass-produced out of plastic, by, for instance, extrusion molding, so that the ;cost per unit be relatively low.

The above embodiment is illustrated with a fiveslide group. It should be understood that the same principle can be used with respect to any desired group from, for instance, two to ten ,and beyond, with each having its specifically dimensioned container, holder, and pool. However, it is contemplated tlat the five-slide arrangements will be the most prevalent:.

Two such five-slide holders can also be clipped back-to-back to create a ten-slide holder. Such ten-slide combination may then be inserted into a ten-slide container, designed in accordance with the invention to accommodate the ten slides.

The container shown above has an overflow comparti ment as described, ׳'.’his is generally desirable when it is anticipated that the slides used vary somewhat in their thickness. Since a thicker slide displaces more liquid, the overflow chamber serves to receive and hold this overflow during the staining operation. Where the slides are relatively uniform in thickness, there is no need for an overflow chamber, since the displacement is more controlled. In this condition, the overflow chamber can be reduced in ־ size, or eliminated, as seen in the embodiment shown in Figfl. 1 to 16.

As an aid in design, the following relations are noted. The distance H₂ by which the level of the top of the pool of staining liquid is raised by immersion of the slides is equal to the volume of the liquid displaced upwardly by the glass of the slides, divided by the average crosssectional area of the glass-free chamber space into which the liquid is displaced. Designating the distance by which the slides are immersed below the top of the original pool as Hp the average cross-sectional area of the chamber above the original pool surface with the slides removed as A^, and the average cross,-sectional area of slide glass in the liquid as A ., then _¥ h, = __________________ ־ ^Ach^/Agl ¹

In the simple case of/a purely rectangular chamber, five slides of 1 mm thickn.sss each spaced .from each other and from the chamber walls by 1 mm, and immersion of the slides to the full depth H qf the original pool, the formula pren diets a rise in liquid level _ Η H _ ל u _s i - _n/5 __χ ״בס. ₂-ץ.

In practice, the height H₂ will be reduced below this value by any extra chamber /space at the edges of the inserted slides, and increase( due to reductions in chamber space caused by tracks in ';he chamber.

While the invention has been described with particular reference to specific embodiments in the interest of complete definiteness, it will be understood that it may be embodied in a variety of forms diverse from those specifically shown and described, without departing from >0 the spirit and scope of the invention as defined by the appended claims.