Presence of extrapancreatic islets of Langerhans in the duodenal wall of the rat.

In the present study we report the existence of typical islets of Langerhans in the duodenal wall of the rat. The nature of the cells and of their corresponding secretory granules were assessed by morpho-cytochemical techniques. The insulin cells formed the core of the islets while the glucagon, the somatostatin and the pancreatic polypeptide cells were located at the periphery. These islets were located in the connective tissue between the duodenal crypts and the muscle layer, neighbouring the last portion of the bile duct. The morphological features of these endocrine cells indicate the presence of high secretory activities which may play an important role in the maintenance of glucose homeostasis, particularly during absorption of nutrients.