Light and electron microscopic observations of glycogen in semi-thin sections employing GMA, Quetol 523 and methylmethacrylate

Abstract

The use of improved GMA-Quetol 523 or GMA-Quetol 523 methyl methacrylate (MMA) mixture as an infiltration medium for the histochemical demonstration of glycogen has been devised to facilitate embedding, sectioning and staining. An improved method of infiltration uses such mixtures with a double weight of QCU-1 as a catalyst. Since the double weight of catalyst prevents interference by bleeding of picric acid from tissue blocks into the resin mixtures, improved mixtures penetrate readily and completely into the tissue fixed in picric acid-formaldehyde-glutaraldehyde solution (PAFG). PAFG solution has been found suitable for the histochemical fixation of glycogen in semithin sections. In hepatocytes specific reaction products appeared a deep reddish-purple after periodic oxidation and Schiff's reaction (PAS reaction), which was lost in previous digestion by means of salivary deastase. Glycogen can be identified as a PAS positive area in semi-thin sections 0.2-0.3 micrometers thick under the light microscope. Identical reactions sites of such sections show a high contrast in electron microscopy without any staining by either heavy metals or osmium tetraoxide vapor. It was therefore demonstrated that total glycogen produced after PAS reaction was revealed distinctly with deep contrast precipitates. This method provides significant morphological data for the histochemical localization of glycogen.