Enterochromaffin cells as the endocrine source of gastrointestinal substance P

Immunoreactive Substance P is localized in the intramural neural plexuses of mammalian intestine, and in endocrine cells in the intestinal mucosa which have now been identified as enterochromaffin (EC). The presence of a neurotransmitter peptide in these cells favours the hypothesis of their neuroectodermal origin.