VAGAL EFFERENT AND AFFERENT INNERVATION OF THE RAT ESOPHAGUS AS DEMONSTRATED BY ANTEROGRADE DII AND DIA TRACING - FOCUS ON MYENTERIC GANGLIA

Anterograde tracing with the carbocyanine tracer DiI and the aminostyr ol derivative DiA was used to selectively label fibers from the nucleu s ambiguus, dorsal motor nucleus and nodose ganglion, respectively, te rminating in the rat esophagus, and to compare them with the innervati on of the gastric fundus in the same animals. Ambiguus neurons termina ted on motor endplates distributed mainly to the ipsilateral half of t he esophagus. There was no evidence of preganglionic innervation of my enteric ganglia from ambiguus neurons. Neurons of the dorsal motor nuc leus supplied sparse fibers to only about 10% of enteric ganglia in th e esophagus while they innervated up to 100% of myenteric ganglia in t he stomach. Neurons of the nodose ganglion terminated profusely on mor e than 90% of myenteric ganglia of the esophagus and on about 50% of g anglia in the stomach. Afferent vagal fibers were also frequently foun d in smooth muscle layers starting at the esophago-gastric junction. I n contrast, they were extremely rare in the striated muscle part of th e esophagus. These morphological data suggest a minor influence of neu rons of the dorsal motor nucleus and a prominent influence of vagal af ferent terminals onto myenteric neurons in the rat esophagus. (C) 1998 Elsevier Science B.V. All rights reserved.