Electron microscopic immunostaining of kallikrein in rat submandibular glands

The subcellular localization of glandular kallikrein in ducts and tubules of the rat submandibular gland was determined using a postembedding immunostaining (peroxidase--antiperoxidase) technique on thin sections of Eponembedded tissue. Kallikrein was found in large granules of granular convoluted tubule cells and in small, apical granules of striated duct cells. It was also present in patchy aggregates along the surface of striated duct cells and intercalated duct cells, but not in granules of the latter. Basal dense bodies (lysosomes?) of granular tubules also stained for kallikrein. Absorption of kallikrein antiserum with rat urinary kallikrein, but not with rat urinary esterase A, abolished the specific immunostaining in these sites.