The histological structure of pigeon intestine (HE staining: 200×). A, duodenum; B, jejunum; C, ileum; D, rectum. Note: a, mucosal epithelium; b, mucous muscle layer; c, muscular layer; d, serosa; e, gland; f, nerve fiber; g, lamina propria; h, lymph nodule; i, goblet cells; j, striatum; k, columnar cells; l, central chyle tube; m, Isolated lymph nodule; n, lymphocyte.