Abstract
The distribution, number, projections and nature of ganglia and ganglionic neurons in the feline larynx were investigated morphologically. Six to eight large oval or spindle-shaped ganglia (including 50-80 ganglionic neurons per ganglion) in rostral portions of the paraglottic spaces, four to six small spindle-shaped ganglions (containing 5-25 ganglionic perkarya in each ganglion) dorsal to the posterior cricoarytenoid muscles and one to three small elliptical ganglia (having 15-25 ganglionic cells in each ganglion) around the inferior laryngeal nerves were observed in the larynx. Each ganglion was covered with a fibrous capsule and ganglionic neurons with a diameter of 25-30μm totaled 600 to 800. Ganglionic neurons received projections from the dorsal motor nucleus of vagus, the superior cervical ganglion (SCG) and the nodose ganglion (NG) ipsilaterally. On the other hand, ganglionic neurons projected to SCG, NG, ipsilaterally and the laryngeal mucosa bilaterally with ipsilateral predominance. Ganglionic neurons showed acetylcholinesterase positive reactions, presumably parasympathetic. On immunocytochemistry, many vasoactive intestinal polypeptide (VIP) -immunoreactive (ir) neurons, and a few tyrosine hydroxylase (TH) -ir and substance P (SP) -ir cells were recognized in ganglions, but no calcitonin gene-related peptide (CGRP) -ir neurons were found. These VIP, TH, SP-ir neurons did not change after denervation of the ipsilateral superior and recurrent laryngeal nerves. Many VIP- and some TH-, SP-, CGRP-ir fibers were also observed around vessels and glandular cells. The present findings show that intralaryngeal ganglionic neurons not only have an endogenic cholinergic nature, but are also involved in local sympathetic and sensory nervous systems.
