Structural evidence for glucagon producing cells in the intestinal mucosa of the rat

Abstract

The gastro-intestinal mucosa of the rat has been systematically studied with the electron-microscope at the following levels: gastric fundus, pylorus, duodenum, jejunum and ileum. Two types of non-digestive epithelial cells have been observed, both exhibiting electron-dense granulations, both candidates for endocrine activity. The first type of cells contains round granules bearing remarkable similarity to the granules of pancreatic endocrine A cells. The second cell type is characterised by strikingly polymorphic granulations and would appear to correspond to the so-called enterochromaffine cells of light-microscopy. On the basis of this morphological criterion, and of the biochemical evidence suggesting the existence of a substance in the intestine which greatly resembles glucagon, biologically and immunologically, it is proposed that this substance is secreted by the first type of cells which resemble the pancreatic A cells. © 1968 Springer-Verlag.