Device for Use in Testing of Fluid Samples on Microscope Slides

This invention relates to a device for use in test procedures wherein a plurality of discrete fluid samples is disposed on one or more microscope slides. For convenience, the device will be described in relation to test procedures in which cells are cultured on the slides, in which procedures the device finds particular application.

At present serum samples to be screened by immunofluorescence techniques are cultured in individual test tubes containing microscope cover slips on to which the cells progressively precipitate. After treatment with a suitable antigen the cells on the cover slips are stained, fixed and examined microscopically.

This method of cell culture is both cumbersome and wasteful of cells and media however and proposals have been made relating to devices in which cells are cultured, treated and examined in situ. For example a device has been proposed comprising a microtitre plate form which the base, including the base portions of the wells, has been removed and replaced by a plurality of microscope slides secured to the plate with a grease. It has been proposed that cells be cultured in the wells of the device and after treatment the slides be removed and examined microscopically. Difficulty has, however, been encountered in obtaining an effective seal between samples in adjacent wells.

Another device has also been proposed which comprises a glass slide to which the ends of the wall portions of a plurality of wells are secured by an adhesive. After cells have been cultured within the wells and treated, the wall portions are broken away from the slide to facilitate microscopic examination. It will be appreciated that as such devices cannot generally be re-used their adoption on a large scale may be unduly costly.

A device has now been produced which overcomes these disadvantages.

According to the present invention a device for use in a test procedure in which a plurality of discrete fluid samples is disposed on a microscope slide comprises a slide support and clamping means for clamping a slide between a gasket provided with a plurality of apertures therethrough and said support, said clamping means being adapted, when actuated, to apply pressure to the gasket whereby said apertures are sealed against said slide in a fluid tight manner to provide a plurality of wells for introduction of fluid thereto.

In practice the device is adapted to carry a plurality of microscope slides each of which provides the base of a plurality of wells, said slides having a thickness in the range 0.8-1.0mm and a length and a breadth generally 76 and 25mm respectively. The clamping means generally comprises a plate adapted to overlay the gasket, said plate being provided with a plurality of apertures therethrough which are in register with the apertures in the gasket. The clamping means is preferably such as to enable a substantially uniform pressure to be applied over the apertured area of the gasket so as to provide leak-proof seals between the slides and the portions of the gasket surrounding the wells.

The gasket is typically fabricated from a sheet of flexible material which withstands repeated autoclaving, such as silicone rubber, and the surface of the gasket is readily removable from the slides with which it is in contact. Removal may be facilitated by coating the surface of the gasket for contact with the slides with a suitable release material such as polytetrafluorethylene.

Particularly when the device is to be used for cell culture in the wells, the slide support, which is generally plate-like in form, is preferably provided with one or more inspection holes therein through which the contents of a well or wells can be examined by means of a microscope e.g. to establish the condition of cells therein.

The slide support is also preferably provided with upstanding portions locating the slides thereon, the upper surfaces of which portions lie level with or, preferably, slightly proud of the surfaces of the microscope slides when the latter are in place on the support. The gasket preferably overlays both the slide and said upstanding portions.

An embodiment of the present invention will now be described by way of example only, with reference to the accompanying drawing which shows an exploded view in perspective of a device suitable for the culture of cells on microscope slides.

Referring now to the drawing, a slide support 1 of stainless steel in the form of a generally rectangular plate 162mm .times. 92mm carried four upstanding stainless steel studs 2 disposed at the corners of a rectangle the edges of which are parallel to the plate 1. The studs pass through apertures (not shown) in a brass template 3 which is secured to the support 1 and which is shaped to locate five glass microscope slides 4 (only one shown) 76 .times. 25 .times. 0.8-1.0 mm is a parallel dispostion on five portions 5 of the support 1. Each of said portions 5 is provided with four circular inspection holes 6 in a staggered arrangement, permitting inspection of the wells by an inverted microscope (not shown.) The surfaces of the microscope slides, when in place, lie slightly proud of the peripheral template surfaces so that good sealing contact can be obtained between the slides and a rectangular gasket of silicone rubber (162 .times. 92 mm) 7, spray coated with polytetrafluorethylene to facilitate release from the slides. The gasket 7 is provided with stud-receiving apertures 8 which allow the gasket to overlay slides 4 on the support 1 and the template 3. The gasket 7 is also provided with ten rows of eight well-forming apertures 9 arranged in pairs so as to lie over the length of five microscope slides 4 (only one shown) carried on the support 1. The gasket 7 is clamped over the slides and template 3 by a plate of stainless steel 10, 162 .times. 92 mm., pressurised by knurled nuts 11 each threadably carried on a stud 2 passing therethrough. The plate 1 is provided with a plurality of well-forming apertures 12 which register with the apertues 9 in the gasket.

When used for screening batches of serum samples by immunoflurescence techniques, the device is first assembled, five microscope slides being clamped between the gasket 7 and support 1, by the plate 10. Eighty wells are thus produced the bases of which are provided by the surfaces of the slides and the walls by the gasket 7 and plate 1. The wells are inoculated with serum, sealed with microtitre tape and incubated at 37.degree.C. Cell monolayers form and adhere to slides and the condition thereof can be determined by inspection with a microscope through the inspection holes 6. Only four of the 16 wells on each slide can be inspected but this is sufficient to provide information on the cell growth in all the wells. The tape is then removed, the cells fixed in situ and subjected to an immunofluorescent testing procedure after which the cells are stained and the device dismantled. After removal of the slides each carrying a plurality of cells samples thereon, the samples are covered with glycerol and coverslips and examined under a microscope.

In further embodiments of the present device the brass template shown in the drawing 3 may be replaced by a template which is not screwed to the slide support 1 as shown in the drawing, but which is provided with a peripheral flange assisting in location of the template by engagement with the sides of the support. The template may be readily removed from the slide support for cleaning.

The inspection holes 6 shown in the drawing may however be disposed in register with the apertures in the gasket and plate 1 if so desired and in this case the number of holes present in the plate is increased to 80, arranged in five paired rows.