[Localization of sensory neurons in the canine nodose ganglion sending fibers to the laryngeal nerves]

Abstract

Afferent fibers from the larynx traverse through the superior laryngeal nerve (SLN) and the inferior laryngeal nerve (ILN), and the parent cell bodies of these fibers are located in the nodose ganglion (NG). However, the exact location and form of these neurons in the NG have not been clarified. The aim of this study is to determine the exact location and form of the sensory neurons in the canine NG which send fibers to the laryngeal nerves, using the retrograde tracer technique with wheat germ agglutinin-horseradish peroxidase (WGA-HRP). The cell bodies sending sensory fibers to the internal and external branches of the SLN (SLNI & SLNE) were localized on the rostro-lateral side of the NG, but the cell bodies sending fibers to the ILN were widely distributed. These findings suggest that the location of cells does not reflect differences in the roles of the cells, but is due to the courses of nerve fibers. The cell bodies sending sensory fibers to the SLNI accounted for about 11% of all cells in the NG; about 0.1% of cells sending fibers to the SLNE; and about 0.2% in the ILN. The cell bodies sending sensory fibers to each laryngeal nerve varied in size, from 15 to 60 microns, suggesting differences in the roles of these cells.