Cytochemical investigation on lipids in human major salivary glands. A light and electron microscope study.

The localization of lipids in the secretion of human parotid and submandibular glands has been here investigated. Ultrastructural observations following lipid extraction and histochemical data showed that lipid components are not present in the secretory granules. In fact, while histochemical reactions are completely negative, secretory granules from lipid-depleted glands retain all their morphological characters. These results led us to emphasize that, at least in human seromucous cells, lipids are not directly involved in the salivary secretion. This conclusion, which is supported by the biochemical data concerning the lipid content in human saliva, disagrees with the findings obtained in rat and guinea pig salivary glands. However, this discrepancy may be ascribed to the specific biochemical and ultrastructural differences found in the salivary glands of the various mammalian species.