Autoradiographic study on the distribution of vagal afferent nerve fibers in the gastroduodenal wall of the rabbit.

Following unilateral supranodose vagotomy which eliminated vagal efferent fibers, [3H]leucine was injected into the ipsilateral no-dose ganglion of the rabbit, which was allowed to survive for 10 days. Autoradiographic examination of the distribution of vagal afferent fibers in the gastroduodenal wall revealed many nerve bundles of labeled afferent fibers present in the subserous plexus between the serosa and the muscle coat, where they branched and descended into the muscle coat. Some of the fibers appeared to interact with some myenteric neurons and muscle fibers in a manner suggesting that the afferent fibers may make synaptic contact with the enteric neurons and innervate or attach to the muscle fibers. Furthermore, the afferent fibers were observed in the submucosal plexus between the muscle coat and the muscularis mucosae. In the mucosa the afferent nerve branched in filaments containing one or several afferent fibers extending from the muscularis mucosae through the mucous lamina propria and to the mucous membrane composed of epithelial cells. It was speculated that the afferent fibers terminated as free endings near the mucous membrane.