1996 Volume 42 Issue 3 Pages 252-260
The presence of a sensory component in the pharyngeal branch of the vagus nerve (PhB), including its peripheral distribution and central projection were studied by denervation and tracer experiments in the cat. The distribution of nerve fibers immunoreactive to protein gene product 9.5, a sensitive neuronal marker, calcitonin gene-related peptide and substance P in the pharyngeal epithelium was analyzed in both intact animals and in animals subjected to partial denervation by means of sectioning two out of the three nervetrunks; consisting of the glossopharyngeal nerve (GPN), the superior laryngeal nerve (SLN) and the PhB, while leaving one intact. The present results show that the GPN and SLN carry nerve fibers to the pharyngeal epitheliumrostral and caudal to the middle level of the epiglottis, respectively, while the PhB carries nerve fibers to the mesopharyngeal epithelium. Tracer experiments, by applying wheat germ agglutinin-horseradish peroxidase to the PhB, demonstrated retrogradely labeled primary sensory neurons in the jugular ganglion and transganglionic labeling of terminals in the interstitial subnucleus of the nucleus of the tractus solitarius (NTSis). These results indicate that the PhB contains a sensory component which originates from the jugular ganglion, innervates the mesopharyngeal epithelium, and projects to the NTSis.
