Identification of the D1-cell as the source of human pancreatic polypeptide (HPP).

Immunoperoxidase positive HPP-producing cells have been examined ultrastructurally using the serial semithin-thin section technique. The features of the HPP cells were found to be identical with those of the previously described D1-cell. The D1-cells are scattered throughout the exocrine parenchyma and occur to a minor extent in the islets.