VASOACTIVE INTESTINAL POLYPEPTIDERGIC INNERVATION OF THE CANINE PANCREATIC ACINAR-CELLS

To provide a morphological basis for understanding the role of vasoact ive intestinal polypeptide (VIP) in the regulation mammalian pancreati c exocrine secretion, the present study was designed to clarify the lo calization and distribution of VIP in the exocrine pancreas, especiall y its relationship with the pancreatic acinar cells. VIP was detected in the dog pancreas using immunoelectron microscopical methods. The pa ncreas was found to contain VIP-immunoreactive (VIP-LR) nerve fibre te rminals. These VIP-IR nerve fibre terminals have in some cases in clos e vicinity with the acinar cells. Some VIP-IR nerve fibres were found in the connective tissue stroma enclosed in Schwann cell processes. It is concluded that the morphological relationship of VIP nerve fibre t erminals to the acinar cells is very intimate. This close association may explain why VIP is a strong bioactive stimulator of the exocrine p ancreas.