GB2089063A - Cytocentrifugation - Google Patents

Abstract

A sample carrier for cytocentrifugation is characterised by a holder with a web 1 dimensioned to support a deposit-receiving slide, for instance a standard microscope slide, and flanges 2 having trunnions 6 for pendulous mounting on a centrifuge head; and a body dimensioned to fit between the flanges of the holder to overlie a slide thereon, the body having through passages defining sample chambers in conjunction with the slide. Seals such as O-rings provide for sealing of the body on the slide and are held in light but seal effective contact with the slide by spring-pressed balls 7 acting between the holder and the body to exert a resilient load on the latter, that is increased by centrifugal forces during centrifuging to maintain effective sealing. A suitable carrier plate (Figs 10 and 11) is provided and replaces that normally supplied with the machine. <IMAGE>

Description

SPECIFICATION Cytocentrifugation THIS INVENTION concerns cytocentrifugation, that is to say the centrifugation of small samples of, e.g., body fluids such as cerebrnspinal fluid, for separating and depositing cells and other solids suspended in the fluid in a manner permitting examination thereof by microscopy. Cytocentrifugation is routinely used in hospital and other laboratories in diagnostic and investigative procedures and needs therefore to be capable of being quickly and easily carried out with repeated utilisation of apparatus that is simple to set up and use.

An object of the invention is to provide cytocentrifugation apparatus that meets these criteria.

Cytocentrifugation apparatus in accordance with the present invention is characterised by a carrier comprising a channel section holder with a web dimensioned to receive and support a depositreceiving slide, and flanges having trunnions for detachable pendulous mounting of the holder on a centrifuge head; and a body dimensioned to fit between the flanges of the holder with a base surface in engagement with a deposit-receiving slide supported by the latter, said body having passages extending therethrough perpendicular to said base surface and sealing means encircling the termination of each said passage in the said base surface, and said holder and said body having complementary cooperative loading means to apply a predetermined resilient loading of the body and said sealing means on the deposit-receiving slide for accomplishing a fluid-tight seal between each said body passage and the deposit-receiving slide.

The said cooperative loading means conveniently serve also as means for detachably securing the body in the holder against inadvertent displacement.

Such means conveniently comprise spring-pressed ball detents in the flanges of the holder and that co-operate with appropriately disposed recesses in the body. The body may have suitably located guide grooves to co-operate with said ball detents to facilitate introduction of the body into the holder and to tend to guide the latter into its proper position in the body by co-operation with the ball detents.

Conveniently the said holder is dimensioned to receive and support a deposit-receiving slide having the dimensions of a standard microscope slide so as to enable such a standard slide to be used as the deposit-receiving slide.

When, as in the case of a standard microscope slide, the deposit-receiving slide is rectangular in shape with one axis substantially longer than the other, and the web of the. holder has a corresponding shape in plan, the flanges of the holder may be disposed at the long sid,es or at the short sides of the web. It is preferred to arrange the holder flanges at the short sides of the web as this arrangement enables the axis defined by the trunnions to lie in the plane containing the axes ofthe passages in the body and facilitates the disposition of the passages, when the body is mounted in the holder, assymmetrically with respect to the length of the depositreceiving slide for a purpose to be explained, without requiring any special provision to ensure that the passage axes align with the gravitational/centrifuge forces acting during centrifugation.

Preferably the holder has slide locating means for locating a deposit-receiving slide in a predetermined position with respect to the web of the holder and to prevent inadvertent displacement of such slide.

Such locating means may conveniently be lugs at the opposite sides of the web, positioned to engage the respective edges of a slide when correctly located with respect to the holder.

Preferably the holder is provided with a resilient backing on its web to underlie and provide resilient support for a deposit-receiving slide. Said backing may conveniently be a layer of elastomeric material bonded or otherwise affixed to the web of the holder.

The said body is preferably provided with two of said passages. The said sealing means are conveniently O-ring or like resilient ring seals housed, and preferably captive, in appropriate recesses in the base surface of the body.

The body may be made of a material appropriate to direct use of its passages as sample chambers but in some embodiments of the invention the body passages may be adapted to receive liners, e.g. of glass, appropriate to contact the fluid samples to be centrifuged by the apparatus and thereby to enable the body to be constructed of a material selected for its physical properties and for ease of construction of the holder without constraints imposed by contact compatability with materials to be centrifuged.

In preferred embodiments of the invention the holder is constructed of hard polyethylene material.

An embodiment of the invention is illustrated in the accompanying drawings, in which FIGURES 1,2 and 3 are, respectively, a side elevation, an end elevation and a plan view of the holder of a sample carrier for cytocentrifugation apparatus in accordance with the invention; FIGURES 4, 5 and 6 are, respectively, a plan view, an end elevation and a longitudinal section on line A-A of Figure 4, of the body of the carrier; FIGURE 7 is a transverse section of the body, on the taxis of one of the passages therein; FIGURE 8 is an enlargement ofthat part of Figure 7 contained within the circle B; FIGURE 9 is a section of a body insert forming part ofthe loading means; and FIGURES 10 and 11 are respectively a plan and a section on line A-A, Figure 10, of a carrier plate suit able for supporting the sample carrier embodiment of Figures 1 to 9.

The drawings illustrate the components of a sam ple carrier for cytocentrifugation apparatus constitut ing one embodiment of the present invention.

Figures 1,2 and 3 illustrate the holder of the car rier. This holder is of basically channel section con figuration providing a web 1 and flanges 2, formed of aluminium alloy in the present embodiment. To withstand the stresses to which the carrier is subject during operation, the web 1 is stiffened by an exter nal longitudinal rib 3. The upper face ofthe web 1 is rectangular in shape with dimensions corresponding with those of a standard microscope slide (75 x 25 mm) and as shown in this embodiment the flanges 2 are at the short sides of the rectangular upper face.

The longer sides of the web 1 of the holder have upstanding central lugs 4 that in use of the carrier engage the corresponding edges of a depositreceiving slide, conveniently a standard glass microscope slide, to prevent lateral movement of the latter when supported by the web 1 of the holder.

The web 1 carries a resilient backing layer 5 (Figure 1) that in operation underlies the depositreceiving slide. The thickness of this backing layer 5 is suitable less than the height of the lugs 4so that these stand proud of the backing layer to perform their slide-locating function. The backing layer is preferably bonded to the web 1.

The flanges 2 have trunnions 6 that are hollow and house spring-pressed ball detent mechanisms the balls 7 of which project inwardly from the flanges 2 ofthe holder.

The illustrated carrierfurther comprises a body shown in Figures 4 to 8. This body is constituted by a block 10 of hard polyethylene material having a length corresponding with the separation of the inner walls of the flanges 2 of the holder and a width corresponding with the width of the web 1 of the holder between the lugs 4. The block 10 has a flat base surface 11.

The body has a pair of passages 12 that extend through the body and open into its base surface 11 and also into its upper surface 13, these passages having their axes on the longitudinal centreline of the body block 10 but being asymmetrically disposed with respect to the transverse centreline for a reason that will be explained. The passages 12 are disposed accurately perpendicular to the base surface 11 and around the opening of each passage into the base surface 11 there is a circular recess 14, concentric with the passage and having the cross sectional configuration shown in Figure 8, that houses a captive O-ring seal 15 (Figure 8) that projects slightly from the base surface 11 and is arranged to form a fluid-tight seal against a deposit-receiving slide when the body is installed in the holder to overlie a slide supported by the web 1 of the latter.

The ends of the body block 10 have aligned blind bores 16 that in this embodiment are each fitted with a steel insert 17 of the form shown in Figure 9 and the outer end of which defines a recess positioned to co-operate with one of the detent balls 7 when the body is installed in the holder.

The bores 16 and their inserts 17 have their axes aligned in the longitudinal central vertical plane of the block 10 and that contains the axes of the passages 12 in the block. As the detent balls 7, with which the inserts co-operate when the block 10 is installed in the holder, are centered on the axes of the trunnions 6, the arrangement provides for the block to be so located in the holder that the axis about which the holder swings is in the plane containing the axes of the passages 12.

Moreover the location of the bores 16 is such that when the block 10 is installed in the holder over a deposit-receiving slide supported by the backing layer 5, the block is held with its base surface 1 T pressing on the slide with a loading, determined by the resilience of the backing layer 5 and the springload on the balls 7, sufficient to ensure adequate sealing, by the O-ring seals 15 on the slide, to prevent leakage of fluid from the passages 12.

To facilitate installation of the body in the holder, the ends of the body block 10 are formed with tapered guide grooves 18 that engage the detent balls 7 and both depress these and, by co-operation with the latter, guide the body into its correct position in the holder as the body is pressed down between the flanges 2 of the latter.

In operation of cytocentrifugation apparatus embodying the sample carrier illustrated in Figures 1 to 9 of the drawings, a suitable deposit-receiving slide such as a standard microscope slide is placed in the holder so as to be located between the lugs 4 at the sides of the web 1 and the body is then installed in the holder so as to overlie the slide.

The passages 12 of the body thereby define, with the surface of the slide, a pair of sample chambers capable of receiving respective samples of fluid to be subjected to centrifugation. If necessitated by contact incompatability between the samples and the material of the body, liners of glass or other suitable material may be installed in the passages 12.

The sample carrier, before or after loading with fluid samples for centrifugation, is fitted to the head of a suitable centrifuge so as to be pendulously supported by the trunnions 6. For reasons of symmetry the centrifuge head will be arranged to be fitted with a plurality of the carriers symmetrically about its rotational axis.

Any suitable centrifuge may be adapted to utilise the sample carriers, by having its head fitted with a suitable carrier plate designed to support a plurality of the carriers bytheir respectivetrunnions 6. Figures 10 and 11 illustrate a suitable carrier plate for this purpose. The carrier plate, generally designated 20, shown in these Figures is designed to support a pair of the sample carriers but it will be understood that it may be modified to support three or more such carriers in a symmetrical array.

The illustrated carrier plate 20 is a circular sheet metal disc with a central aperture 21 bordered by a stepped central area 22 of the disc and intended to fit over a correspondingly stepped hub of the head of a centrifuge, the illustrated configuration being adapted to fit the stepped hub of a cytocentrifuge of the construction described in our co-pending European Patent Application No.81105670.4, in replacement for the described carrier plate of that machine.

The periphery of the carrier plate disc is turned down into a stiffening flange 23.

At diametrically opposed locations, the carrier plate disc has apertures 24 the ends of each of which are defined by downturned flanges 25 having slots 26, merging with slots 27 in the adjacent disc, to receive the trunnions 6 of the holder of a sample carrier as above described. Thus a pair of such carriers may be pendulously supported, detachably, by their trunnions in the carrier plate, so as to be capable of swinging outwardly under centrifugal loads when the carrier plate is rotated.

During a subsequent centrifuging operation the pendulous support of the sample carrier by the trunnions 6 will result in the carrier adopting an attitude such that the axes of the passages 13 are aligned with the resultant centrifugal force and stratification of sample material will occur with density strata parallel with the deposit-receiving slide and the deposition on the latter of the densest material in a uniform layer on the slide. When the required deposition has occurred and the centrifuge has been brought to rest, liquid in the sample chambers may be removed by pippetting and the sample carrier dismantled for removal of the slide bearing the deposited material.

The asymmetrical disposition of the passages 12 with respect to the transverse centreline of the holder provides for deposition of material correspondingly asymmetrically upon the slide so a sufficient area at one end of the slide will be clear of deposited material and available for carrying a slide identification indicia.

It has been explained how the detent balls 7 cooperate with the recesses 16 in the body both to locate the body in the holder and to secure it with a suitable resilient loading upon the deposit-receiving slide for the O-ring seals 15 to prevent leakage of fluids from the sample chambers constituted by the passages 12 in conjunction with the slide. Whilst the carrier is subject to normal gravity, i.e. when the centrifuge is at rest, only a relatively light pressure is required to achieve effective sealing of the sample chambers. However, it will be understood that under centrifugal force fields during centrifuging a much higher pressure is required to maintain an effective seal.This higher pressure is automatically generated, in the carrier construction of the invention, by the centrifugal force acting on the block 10 during centrifugation and tending to force this down, in the holder, against the slide. Such slight movement of the block as is necessary to take up the resilient yielding of the backing layer 5 and to allow development of the required pressure of the block upon the slide is unimpeded by the detent balllrecess structure.

Accordingly, the carrier of the invention is of lowcost construction, and provides both for extremely simple assembly and dismantling of its very few components, and the obtaining of a reliable leak-free sealing of the sample chambers, without complicated mechanical clamping arrangements and with only small forces acting on the (usually frangible) slide under static conditions and the avoidance, thereby, of the dangers of slide breakage and/or sample chamber leakage by the loads arising during centrifugation.

Claims (13)

1. Cytocentrifugation apparatus characterised by a carrier comprising a channel section holder with a web dimensioned to receive and support a depositreceiving slide, and flanges havingtrunnions for detachable pendulous mounting of the holder on a centrifuge head; and a body dimensioned to fit between the flanges of the holder with a base surface in engagement with a deposit-receiving slide supported by the latter, said body having passages extending thereth rough perpendicular to said base surface and sealing means encircling thetermination of each said passage in the said base surface, and said holder and said body having complementary cooperative loading means to apply a predetermined resilient loading of the body and said sealing means on the deposit-receiving slide for accomplishing a fluid-tight seal between each said body passage and the deposit-receiving slide.

2. Cytocentrifugation apparatus according to claim 1, wherein said cooperative loading means serve also as means for detachably securing the body in the holder.

3. Cytocentrifugation apparatus according to Claim 2, wherein said cooperative loading means comprise spring-pressed ball detents in the flanges of the holder and that cooperate with recesses in the body.

4. Cytocentrifugation apparatus according to Claim 3, wherein the body has guide grooves to cooperate with said ball detents during introduction of the body into the holder.

5. Cytocentrifugation apparatus according to any preceding claim, wherein said deposit-receiving slide has a rectangular shape with one axis longer than the other and the holder web has a corresponding shape, the flanges of the holder being disposed at the short sides of the web.

6. Cytocentrifugation apparatus according to any preceding claim, wherein the holder has slide locating means for locating a deposit-receiving slide in predetermined position with respect to the web of the holder.

7. Cytocentrifugation apparatus according to Claim 6, wherein said slide locating means comprise lugs at opposite sides of the holder web and positioned to engage corresponding edges of a slide correctly positioned in the holder.

8. Cytocentrifugation apparatus according to any preceding claim, including a resilient backing on the web of the holder to underlie and resiliently support a deposit-receiving slide.

9. Cytocentrifugation apparatus according to Claim 8, wherein said backing is a layer of elastomeric material bonded to the web of the holder.

10. Cytocentrifugation apparatus according to any preceding claim, wherein said body has two of said passages.

11. Cytocentrifugation apparatus according to any preceding claim, wherein said sealing means comprise O-ring seals housed in recesses in the base surface of the body.

12. Cytocentrifugation apparatus substantially as described with reference to and as shown in the accompanying drawings.

13. Every novel feature and every novel combination of features disclosed herein.