A comparative study of the portal vessels connecting the endocrine and exocrine pancreas, with a discussion of some functional implications.

We have examined the pattern of the capillaries of the pancreas in rabbits, rats, mice, guinea-pigs, cats and baboons, using arterial and venous injections of Berlin blue. In all these species we found extensive, direct connexions between the capillary beds of the islets and the exocrine tissue of the gland, forming a highly developed portal system. Some of the functional implications of these vascular connexions are discussed, particularly the influence of the islet hormones insulin, glucagon and somatostatin upon the exocrine cells.