Histological analysis of the sublingual gland in rats with streptozotocin-induced diabetes.

This study was designed to examine whether the sublingual gland parenchyma is influenced by the development of insulin-dependent diabetes mellitus. The sublingual glands of rats with streptozotocin-induced diabetes were examined by light and electron microscopy. In order to define the limiting membrane of mucous granules in more detail, samples processed by rapid freezing following by freeze-substitution in addition to chemical fixation were also prepared for electron microscopy. Light and electron microscopy showed vacuole-like structures considered to be lipid droplets in the cytoplasm of serous demilune cells, the largest reaching 4 microm in diameter. Electron microscopy of the chemically fixed samples revealed granule-like structures in addition to the mucous granules proper in the mucous cell cytoplasm. However, electron microscopy of the freeze-substitution fixed samples demonstrated no limiting membrane on the surface of the granule-like structures, although this was clearly observed on the surface of the mucous granules. Accordingly, the granule-like structures present in the mucous cell cytoplasm appeared to be lipid droplets. These findings suggest that the sublingual gland mucous cells become dysfunctional during the development of insulin-dependent diabetes mellitus, although to a slighter degree than the serous demilune cells.