Serotoninergic neurons in human fetal intestine: an immunohistochemical study.

The distribution of 5-hydroxytryptamine-like immunoreactivity was studied in whole-mount preparations of intestine from human fetuses. Immunoreactive nerve cell bodies were located in the myenteric plexus and were occasionally found in the submucous plexus; they were often seen to have long processes. Varicose fibers were found in the ganglia and internodal strands of the myenteric and submucous plexuses, in the deep muscular plexus of the circular muscle, and in the walls of some small mesenteric blood vessels immediately outside the intestine. This study provides evidence for the presence of serotoninergic nerves in the human intestine.