A rich VIP nerve supply is characteristic of sphincters.
D000818:Animals; D002415:Cats; D004386:Duodenum / Q000294:innervation*; D004745:Enkephalins / Q000502:physiology; D004947:Esophagus / Q000294:innervation*; D005260:Female; D005768:Gastrointestinal Hormones / Q000502:physiology*; D008297:Male; D009130:Muscle, Smooth; D018377:Neurotransmitter Agents / Q000502:physiology; D013270:Stomach / Q000294:innervation*; D013373:Substance P / Q000502:physiology; D014513:Ureter / Q000294:innervation; D014660:Vasoactive Intestinal Peptide / Q000502:physiology*
D004745:Enkephalins; D005768:Gastrointestinal Hormones; D018377:Neurotransmitter Agents; D013373:Substance P; D014660:Vasoactive Intestinal Peptide