Abstract
The histochemical reaction for acid trimetaphosphatase in addition to secondary tissue treatment with an osmium-ferrocyanide mixture was used to study lysosomes and phagolysosomes in the mouse thyroid gland. The osmium-ferrocyanide postfixation enhanced reaction product localization, reduced diffuse reaction, and improved membrane contrast. In addition, the ultrathin tissue sections did not require heavy metal staining, thus eliminating potential stain artifacts due to precipitation. In view of the improved tissue preservation and enzyme localization, it is suggested that osmium-ferrocyanide postfixation be used after the acid trimetaphosphatase method.