IMPROVED METHOD FOR POSTEMBEDDING CYTOCHEMISTRY USING REDUCED OSMIUM AND LR WHITE RESIN

We established an improved method for post-embedding cytochemistry by which highly specific cytochemical reactions on excellent cellular ult rastructures are possible. The method is a combination of post-fixatio n in potassium ferrocyanide-reduced OsO4 and embedment in acrylic-base d LR White resin. It permits both immuno- and lectin-gold cytochemistr y with fine ultrastructures comparable to those obtained by convention ally osmicated and expoxy-embedded tissues. Fixation with reduced osmi um appeared to contribute to the preservation of immunoreactivity and membranous structures. By this method, the immunocytochemical localiza tion of secretory proteins (amylase and chymotrypsinogen), actin filam ents by polyclonal antibodies, 105 KD Golgi-associated protein by a mo noclonal antibody (GF-1), and binding sites for gold-labeled lectin co uld be demonstrated. Also possible was multiple staining with enzyme c ytochemistry of thiamine pyrophosphatase and immunocytochemistry of GF -1 and anti-amylase antibodies. This multiple staining made possible p artial characterization of the trans-Golgi network in parotid acinar c ells.