The neuro-endocrine complex in the gastro-entero-pancreatic endocrine system

The pancreatic islet is one of the well-studied endocrine tissues in regard to innervation. This neuro-insular complex has been known since the 1920's. The direct contact of the nervous element to the gastro-enteric endocrine cells has recently been reported in the proventricular mucosa of the finch. Here, the majority of the endocrine cells lie in the lamina propria and form a neuro-endocrine complex with unmyelinated nerve fibers. A similar neuro-endocrine complex was also reported in the rat stomach and in the duodenum of the human fetus. The occurrence of the neuro-endocrine complexes in the gastro-entero-pancreatic endocrine system might provide supportive data to the neuro-ectodermal theory on the origin of the endocrine cells proposed by Professors A. G. E. PEARSE and T. FUJITA.