Ultrastructure and enzyme histochemistry of the pancreatic islets in the horse.

Abstract

The characteristic localization of the silver-negative A2 cells in the central part of the pancreatic islets in the horse offers a good opportunity to study the ultrastructure and histochemistry of this type of islet cell. Electron microscopical analyses revealed that the A2 cells contained dense spherical granules varying considerably in size. Light and dark A2 cells were identified. The presence of numerous secretory granules of very low density was the most conspicous feature of the B cells. These cells also showed considerable differences in density. A second type of peripheral islet cell was characterized by a very high content of mitochondria and ribosomes. These small islet cells contained tiny granules and are probably identical with the A1 cells.