Histological studies on the endocrine pancreas in the dog.

Based on histological structure and cellular formation, the endocrine pancreas (pars endocrina pancreatis) (PEP) or pancreatic islet (insulae pancreaticae), was divided into two types in the dog. One type of PEP was the islet of Langerhans. In the glandular lobule, the islet was surrounded by exocrine acini. The other type of PEP, in general, exhibited a feature of a neuro-insular complex. It was found within the interlobular connective tissue of the pancreas. This type of PEP was attached to a nerve bundle or ganglion. In the pancreas of the immature dog, a large population of endocrine cells was recognized to form a blood islet within the neuro-insular complex.