Anatomy of the myenteric plexus of the opossum esophagus.

Silver-impregnated stretch preparations of the opossum esophageal body and lower esophageal sphincter were compared as to the general aspect of the plexus, density of perikarya and ganglia, type and size of ganglia, nerve bundle diameter, density of nerve bundle intersections, and relations between ganglia and nerve bundle intersections. Density of perikarya and ganglia, but not density of nerve bundle intersections, declined along the esophagus, with a nadir at the sphincter. The proximal body contained 960-1358 perikarya/cm2 and the sphincter, 70-333 perikarya/cm2. Ganglia contained 3-100 cells, 54% having less than 10. Many small ganglia lay outside nerve bundles (parafascicular ganglia), the proportion being greatest in the sphincter (25%-54%). Many ganglia (15%-22%) were remote from nerve bundle intersections and many intersections were remote from ganglia, 28%-35% in the body and 66%-69% in the sphincter. Nerve bundle diameter was a single population with a skewed distribution; the mode was about 0.1 mm.