Types of pancreatic islet cells and their immunocytochemical identification.

In the Lausanne classification of islet cells which is based mainly on the ultrastructural characteristics of secretion granules, a total of nine different cell types have been described. By immunocytochemistry at least 12 different hormones or peptides have been either detected or postulated as being within cell types in the pancreatic islets. The cells responsible for the secretion of insulin, glucagon, GIP, pancreatic polypeptide and somatostatin have been firmly established. The identification of cells containing VIP, secretin, gastrin, biogenic amines and other peptides still remain tentative. The development of immunocytochemical techniques and their use at the light microscopic and ultrastructural level have been of immense value in the recognition of islet cell types and the peptides that they contain. Continued improvement in the purification of islet hormones and specific antibodies to these hormones together with correlative and immunocytochemical studies should lead to a better understanding of normal islet cell function, and thus hopefully, the cellular abnormalities encountered in tumors of the endocrine pancreas.