Ultrastructural cytochemistry of the secretory granules of the hamster submandibular gland.

The ultrastructure and cytochemistry of the secretory granules of the male hamster submandibular salivary gland were studied; After fixation in glutaraldehyde followed by osmium tetroxide the granules exhibit a characteristic bipartite substructure, with an electron lucid crescenteric rim and a more dense central core. A differentiation into two regions of the granules could also be visualized in specimens primarily fixed in Millonig's osmium tetroxide or in potassium permanganate. The electron lucid peripheral portion of the membrane bounded secretory granules further displays a strong positive reaction after staining of ultrathin sections with the periodic acid-chromic acid-(PA-CrA)-silver technique. The strong periodate reactivity of the rim relative to the core, suggests a difference in mucin composition of the two granule regions. With the PA-CrA-silver straining technique a positive reaction was also observed within the Golgi apparatus of the acinar cells.