ABSTRACT
The ability of the enteric nervous system to mediate reflex activity, even when isolated from the brain and spinal cord, is the physiological characteristic that most strikingly distinguishes the intrinsic innervation of the gut from that of any other peripheral organ. Recent experiments in which vagal efferent terminals were identified with an anterograde tracer support the idea that many enteric neurons do not receive a central nervous system innervation, although there are many vagal motor terminals in the gut, especially in the stomach. Enteric neurons project out of the gut to innervate pancreatic ganglia, the ganglionated plexus of the gallbladder, and prevertebral sympathetic ganglia. Surprisingly, the crest-derived emigres that colonize the bowel are not committed to develop specifically as enteric neurons or glia, either at the time they depart from the crest or even after they have completed their migration and arrived in the gut.
