A SIMPLE TECHNIQUE FOR FLAT OSMICATING AND FLAT EMBEDDING OF IMMUNOLABELED VIBRATOME SECTIONS OF THE RAT SPINAL-CORD FOR LIGHT AND ELECTRON-MICROSCOPY

We describe here a simple technique for flat-osmicating and flat-embed ding of immunolabelled vibratome sections. The technique is particular ly useful for large specimens such as whole cross-sections of rat spin al cord. After the vibratome section has been flat-osmicated on a flat surface under a glass coverslip, it is dehydrated and then embedded b y placing it in a small drop of epoxy resin on a flat base of polyprop ylene plastic and overlaying a small square piece of cellulose acetate cut from heat-resistant overhead projector transparency film for phot ocopying. The thin layer of resin containing the flat-embedded vibrato me section is then separated from the base and glued onto the flat end of a pre-polymerised blank block of resin. The method produces flat-e mbedded vibratome sections and thus allows serial large uniformly labe lled semithin and ultrathin sections to be obtained of the whole cross -section of the rat spinal cord. This facilitates the observation and quantification of labelled cells in the specimen. Because of its simpl icity the technique also allows one worker to process more than 100 vi bratome sections at the one time.