Immunohistochemical examination of VIP in various segments of pigeon’s intestine (Immunohistochemical staining: 400×). A, duodenum; B, jejunum; C, ileum; D, Rectum; E, Duodenum-villi; F, Jejunum-fluff; G, Ileum-fluff; H, rectum-fluff. Black arrows pointing VIP positive cells.