Ultrastructure of mink submandibular gland

The submandibular gland of the North American mink, a strict carnivore, was studied by light and electron microscopy. The gland is mixed in nature, consisting of mucous tubules capped by mucous demilunes. Mucous droplets in the tubule cells are structureless, but those in the demilune cells contain a dense spherule. Intercalated ducts are extremely short. Striated duct cells contain numerous crystalloids, often rhomboidal, in their apical cytoplasm. These crystalloids are equally abundant in males and females. The presence of these structures lends credence to the supposition that in addition to their role in electrolyte transport, striated ducts may be actively engaged in secretion of organic products.