A dense plexus of CGRP-immunoreactive nerve fibers in portions of the major salivary excretory ducts close to their opening into the oral cavity of rats.

A dense plexus of CGRP-immunoreactive nerve fibers was found subjacent to and within the epithelium of the excretory ducts of the parotid, submandibular and sublingual glands in the rat, in close proximity to the opening into the oral cavity. The immunoreactive nerve fibers disappeared after a neonatal administration of capsaicin. In immuno-electron microscopy, the immunoreactive nerve fibers were characterized by abundant small clear vesicles mixed with some large granular vesicles, but not by any particular abundance of small mitochondria. Intraepithelial immunoreactive fibers were directly apposed to adjacent epithelial cells without any membrane specializations. They did not exceed the subapical junctional complex of the epithelial cells.