POLYCHROMATIC STAINING OF EPOXY SEMITHIN SECTIONS - A NEW AND SIMPLE METHOD

A simple, rapid method is described for the polychromatic coloration o f semithin sections, which is applicable to material routinely process ed for transmission electron microscopy. Material fixed with a glutara ldehyde-paraformaldehyde mixture and postfixed in osmium tetroxide wit h or without potassium ferrocyanide and embedded in different types of resin (Durkupan-ACM, Spurr resin, Taab resin) can be used. Constant a nd homogenous results are obtained with this technique, the staining p rocedure being achieved at room temperature in no more than 10 min. Se ctions of 0.5-1 mum in thickness are oxidised and bleached. After wash ing, sections are stained in two steps with carbol methylene blue/carb ol gentian violet solution and pararosaniline solution. Using the meth od described in this paper, a polychromatic coloration of the differen t cells and tissues was obtained (epithelial cells in various shades o f blue-violet, connective tissue and elastic laminae of blood vessels in pink or red, etc.). This procedure provides greater contrast betwee n cytoplasm and nuclei, and among the different types of cells and tis sues than is seen with toluidine blue, which is very useful for observ ation and photography of semithin sections. Polychromatic methods foun d in the literature are normally complex and require a lengthy stainin g time or cannot be applied on material routinely processed for transm ission electron microscopy. Our method is simple, rapid and can be use d on any type of material routinely processed for transmission electro n microscopy and embedded in epoxy resins.