An immunohistochemical study on the distribution of endocrine cells in the chicken gastrointestinal tract

The distribution and the frequency of occurrence of nine types of gut endocrine cells were revealed using immunohistochemical methods in eight portions from the gastrointestinal tract of the chicken (Gallus gallus var domestica). In the proventriculus, somatostatin- and gastrin-releasing polypeptide (GRP)-immunoreactive cells were commonly found. Serotonin-, pancreatic glucagon-, and enteroglucagon-immunoreactive cells were uncommon. Avian pancreatic polypeptide (APP)-immunoreactive cells were rare. In the gizzard, numerous GRP-, and a small number of somatostatin-immunoreactive cells were observed. The pyloric region was characterized by the presence of abundant gastrin-, somatostatin-, and neurotensin-immunoreactive cells. Numerous serotonin-immunoreactive cells were detected in all portions of the intestine. Moderate numbers of neurotensin-immunoreactive cells were detected in all portions of the intestine except for the cecum. A few gastrin- and somatostatin-immunoreactive cells were detected in the duodenum and jejunum. A small number of pancreatic glucagon-immunoreactive cells were detected in the jejunum and ileum. Enteroglucagon-immunoreactive cells were detected in the small intestine in increasing numbers forwards the ileum. Motilin-immunoreactive cells were rare in the small intestine.