Distributions of the calcitonin gene-related peptide and substance P in the monkey larynx

Abstract

The distribution of calcitonin gene-related peptide (CGRP)- and substance P (SP)-like immunoreactivity in the monkey larynx was studied with light microscopy using the immunofluorescence method. We divided the larynx into the following six regions: epiglottis, arytenoid region, false cords, ventricle, vocal cords and subglottis. The distribution of immunoreactivity in the epithelium and subepithelial layer was determined. CGRP- and SP-like immunoreactive nerve fibers were observed in all regions of the laryngeal epithelium except in the vocal cords. In the epithelium of the epiglottis and arytenoid region, numerous taste buds containing several CGRP- and SP-like immunoreactive nerve fibers were observed. In the subepithelial layer, CRGP- and SP-like immunoreactive nerve fibers were observed in all regions of the larynx. In order of decreasing density, these fibers were found in the arytenoid region (especially the corniculate tubercle), the epiglottis, the false cords, the subglottis, the ventricle, and the vocal cords. In the corniculate tubercle, CGRP- and SP-like immunoreactive nerve fibers formed a network, whereas around the cuneiform tubercle, dense CRPG- and SP-like immunoreactive nerve fibers were noted parallel to the basement membrane. SP-like immunoreactive nerve fibers showed a very similar distribution to the CRPG fibers in the epithelium and the subepithelial layer, but SP-like fibers were sparser in all regions of the larynx. These results, together with previous findings indicate that the arytenoid region and the epiglottis of the monkey larynx play very important roles in airway protection, swallowing, and respiration.