GB1405940A - Apparatus for processing tissue for electron microscope examination - Google Patents

Abstract

1405940 Preparing specimens for electron microscopy SAKURA SEIKI K K 10 Nov 1972 51936/72 Heading G2J An apparatus for preparing a specimen for electron microscopy by dipping it successively in various reagents at various temperatures for various lengths of time has means for effecting some of the immersions under reduced pressure, and comprises an annular hollow jacket member 40 having a series of cylindrical pockets 54 each containing a reagent receptacle 12. A disc 5 is mounted on a shaft 6 rotated with an indexing motion via a geneva mechanism 25, 26 and oscillated vertically by a cam 27. The disk 5 carries depending rods 7, one of which, of adjustable length, carries a basket 9 for the specimen and a sealing cap 8 which co-operates with an annular pad 60 around each receptacle 12 to seal it; the other rods 7 carry spring-mounted lids 10 adapted to seal the other receptacles 12 to prevent evaporation. The basket 9 is agitated in the reagent by a driven crank mechanism 113. Upon withdrawal from a viscous reagent the basket 9 may be held stationary over the receptacle 12 for a time to allow reagent to drip back into the receptacle 12. Some of the cylindrical pockets 54 are connected via solenoid valves 76 and filters to a vacuum pump 75 so that the immersion of the specimen in some of the reagents may be accomplished under reduced pressure. To heat or cool the reagents water is circulated through the annular jacket member 40 from a reservoir 44 provided with a refrigerating coil 50 and two heating coils 51, 52 thus giving three possible operating temperatures; thermostatic control may be provided. The apparatus is covered and sealed by a hood 4 connected to an exhaust system 80-86 for noxious gases. Dry filtered air is supplied to the interior of the hood through a pair of silica gel drying devices, one such device undergoing a heated recovery process while the other is operating. A main electric motor 15 provides the two motions of the shaft 6 under the control of a main timer. The receptacles containing viscous reagents have adjacent micro-switches 100 whose closure by a pin 101 depending from the disk 5 activates a system of relays connected to the main timer, and to a secondary timer, to provide for the delay in the motion of the specimen while the reagent drips back into its receptacle 12. Specific concentrations for the reagents, which include glutaraldehyde, cacodylate buffer, osmic acid, alcohol, propylene oxide, and liquid "Epon" resin, are disclosed; immersion times range from 10 minutes to 120 minutes; the temperatures involved are 4‹C, 20‹C and 37‹C.