Immunocytochemical study on the innervation of the chicken pancreas by vasoactive intestinal polypeptide (VIP)-containing nerves.

Ultrastructural localization of vasoactive intestinal polypeptide (VIP) was studied in the chicken pancreas by the immunocytochemical method. VIP-immunoreactive nerve endings were found in contact with acinar cells in the pericapillary space or between acinar cells. They also terminated on epithelial cells of arteriolae. In pancreatic islets, VIP-immunoreactive nerve endings were in contact with B-cells, but not with A- or D-cells. VIP-immunoreactive terminals contained many small clear vesicles which indicate the cholinergic feature. Nerve endings containing many small clear vesicles but not showing VIP-immunoreactivity were also detected in both the exocrine and endocrine pancreas. According to these data and the previous studies concerning the cholinergic and VIPergic innervation of the chicken pancreas, it is suggested that VIP-containing cholinergic nerves innervate B-cells and cholinergic nerves not containing VIP innervate D-cell.