MORPHOLOGICAL RELATIONSHIPS OF CHOLERAGENOID HORSERADISH PEROXIDASE-LABELED SPINAL PRIMARY AFFERENTS WITH MYENTERIC GANGLIA AND MUCOSAL ASSOCIATED LYMPHOID-TISSUE IN THE CAT ESOPHAGOGASTRIC JUNCTION

The goal of the present study was to gain insight into the environment al factors influencing the activity of primary spinal afferent fibers in the different layers of the esophagogastric junction of the cat and , thus, to analyze the relationships of these afferents with various c ellular components. Spinal primary afferent fibers were selectively la beled by anterogradely transported choleragenoid horseradish peroxidas e conjugate (B-HRP). B-HRP was injected into the thoracic dorsal root ganglion at the T8-T13 levels. 6-Hydroxydopamine-induced sympathectomy was performed prior to B-HRP injection in order to prevent otherwise unavoidable labeling of sympathetic fibers in the gut wall. Numerous l abeled fibers ran between, around, and within the myenteric ganglia. O thers crossed the muscle layers directly and entered the mucosa, where some ran near granulocytes and around or through solitary lymphoid fo llicles. Labeled fibers were observed in the squamous esophageal epith elium but not in the fundic glandular epithelium. The fibers in the my enteric area are probably connected to the muscular tension receptors that have been detected by electrophysiologic techniques. This assumpt ion is based on the observation that only a few fibers appear to termi nate in muscle layers and on the fact that the myenteric area is very narrow and subject to powerful forces. Fibers in the myenteric ganglia could be involved in local efferent functions. Fibers in the mucosa c ould act as nociceptors and might be involved in local immunological r esponses. (C) 1994 Wiley-Liss, Inc