Neurochemical markers in the nervous plexus of the canine glottis

Abstract

The structure of the nervous network and the distribution of tyrosine hydoroxylase (TH)- and various neuropeptide-containing nerves were immunohistochemically studied in the glottis of the dog. The nervous network in the glottis revealed apparent regional differences in morphology. The nervous network in the cartilaginous vocal fold of the posterior glottis consisted of nerve bundles running parallel to the edge of the vocal fold. Only a small number of nerve bundles were observed in the anterior glottis, specifically in membranous vocal fold. In the subepithelial layer of the posterior glottis, a moderate number of galanin (GAL)-immunoreactive nerve fibers were observed, while only a few fibers were present in the anterior glottis. Numerous vasoactive intestinal peptide (VIP)-, GAL-, methionine–enkephalin (ENK)- and TH-immunoreactive nerve fibers were observed within and around the laryngeal submucosal seromucous gland. Many TH- and neuropeptide Y (NPY)-immunoreactive fibers were arranged around the blood vessels. In the epithelia, free nerve endings with immunoreactivity for substance P (SP) and calcitonin gene-related peptide (CGRP) was observed. Furthermore, nerve cell bodies with SP-, VIP-, GAL-, ENK-, and NPY-immunoreactivity were observed in the deep region of the submucosal layer. The results from the present study suggest that there is autonomic regulation of the glottis. Regional structural differences in the nervous network of the glottis may reflect functional differences.