The endocrine pancreas of the rat following portacaval shunt.
Four weeks after portacaval shunt the pancreatic islets of rats underwent pronounced morphological changes. A cells showed few organelles and had a large amount of secretory granules which often appeared to swell and fuse into one another. B and D cells on the contrary had well developed rough endoplasmic reticulum and Golgi complex, numerous immature granules and a few mature granules; the latter often underwent exocytosis. In the peripheral area of the islets possible preinsular cells were frequently observed. such cells and typical D cells were also found outside the islets in the walls of ductules lying near the islets. Such findings suggest a functional inhibition of A cells and an enhancement of the secretory activity of B and D cells. Moreover a differentiation of islet cells from ductular cells seems to occur. Such a process seems to lead to neogenesis of D and probably of PP cells. The experimental data reported here should be considered in view of their possible implications in clinical medicine.