Immunogold labeling of peroxidase in salivary gland acinar cells using an improved tissue preparation procedure: rapid freezing and Lowicryl embedding.

The immunocytochemical localization of peroxidase in the acinar cells of the Mongolian gerbil parotid gland was studied using aldehyde-fixed tissue prepared by rapid freezing and low-temperature embedding in Lowicryl K4M resin. This freeze-embedding method was developed to provide improved preservation of cell ultrastructure and optimum accessibility of antigens, combined with relative technical ease. Immunogold labeling with antibody to peroxidase was found mainly in the dense cores of mature and immature secretory granules. In the trans Golgi area, the rough endoplasmic reticulum (rER), many clusters of smooth vesicles, and short tubular structures showed a variable labeling intensity. The results demonstrate the utility of this newly-developed preparative method and confirm the presence of peroxidase in elements of the Golgi apparatus.