Distribution of intraepithelial nerve fibers in the feline glottis

It is well known that the protective laryngeal closure is elicited by mechanical or chemical stimulation of the epithelium in the glottis. In this study we used light microscopic observation and relative examination of the intraepithelial nerve fibers in the glottis to clarify the perceptive mechanism using immunohistochemical methods. In the anterior glottis, a moderate number of protein gene product 9.5-immunoreactive intraepithelial nerve fibers were observed, most of which were found to be located just anterior to the vocal process. The number of fibers in the upper surface of the vocal fold was larger than that in the free edge and the lower surface. Only a few calcitonin gene-related polypeptide-immunoreactive fibers were seen, and substance P-immunoreactive fibers were rarely seen. On the other hand, a dense distribution of protein gene product 9.5-immunoreactive nerve fibers was observed throughout the epithelium of the posterior glottis. The number of calcitonin gene-related peptide-immunoreactive fibers was about 20% that of protein gene product 9.5-immunoreactive fibers, whereas the number of substance P-immunoreactive fibers was only 1% to 2%. The results of this study suggest that possible existence of regional differences in the perceptive mechanism between the anterior and posterior glottis.