Cellular localization of kallikreins in rat submandibular and sublingual salivary glands: immunofluorescence tracing related to histological characteristics

Abstract

Immunohistochemical localization of rat salivary gland kallikrein was related to glandular structures in tissue processed and stained by various methods. In the submandibular gland, most of the kallikrein was located to cytoplasmic granules of the granular tubules. Cells of the striated ducts showed a faint cytoplasmic staining with a bright luminal rim that occasionally was seen also in the excretory ducts. Minor amounts of kallikrein was found in the interstitial tissue. In the sublingual gland, kallikrein was found in the cytoplasm of the striated duct cells and as a luminal rim in the main ducts. Acini were negative in both glands. Fixation in Helly's fluid preserved cytoplasmic granules and was thus superior for intracellular localization of kallikrein, whereas ethanol fixation, due to absence of non-specific background staining, afforded the most sensitive method for detection of small amounts of antigen. In the submandibular gland, best identification of granular tubules and striated ducts was achieved with DMAB-nitrite staining for tryptophan and counterstaining with Mayer's haemalum on sections of tissue fixed in Helly's fluid. In the sublingual gland, the duct system was best demonstrated by haematoxylin-eosin staining.