Comparative aspect on the innervation of submandibular glands in cat and rabbit: an electron microscopic study.

Abstract

The innervation of the submandibular glands of cat and rabbit was studied by electron microscopy. The acini of the submandibular glands of both species were composed of myoepithelial cells and two types of secretory cell; namely, acinar and demilunar cells in the cat, and neck and acinar cells in the rabbit. In the peri-acinar connective tissue there were both adrenergic and cholinergic nerve endings which were differentiated by their contents of synaptic vesicles, especially of small granular vesicles. These nerve endings were surrounded partly or completely by Schwann. cell cytoplasm. On the other hand, only one type of nerve ending (cholinergic) was observed within the acini. These intra-acinar nerve endings were devoid of Schwann cell sheath, contacted directly with the plasma membranes of the myoepithelial cells and of the one type of secretory cell that was close to the intercalated duct; namely, the acinar cells in the cat and the neck cells in the rabbit. The occurrence of the nerve endings within the acini was seen more frequently in young cats but somewhat less in adult cats. The functional significance of the intra-acinar nerve endings is discussed.