Fine structure of Duvernoy's gland of the Japanese colubrid snake, Rhabdophis tigrinus.

Duvernoy's gland (a type of venom gland) of the Japanese colubrid snake, Rhabdophis tigrinus, was examined by electron microscopy. The secretory units of the gland consist of the secretory and myoepithelial cells. The secretory cells are columnar in shape and have well-developed rough endoplasmic reticulum (RER), Golgi apparatus and mitochondria in the basal perinuclear cytoplasm. The secretory granules are homogeneous in structure and moderately dense. They are accumulated in the apical cytoplasm and are released by exocytosis into the lumen. The myoepithelial cells often enclose the secretory units, contain bundles of filaments in the cytoplasmic process, and are innervated by the free endings of the autonomic nerves through the basement membrane. In addition, many nerve terminals end in pericapillary spaces, suggesting a release of neurosecretions into the blood. The duct epithelium is composed of typical mucus secreting cells, whose cytoplasm contains secretory globules of lower electron density.