Development of islet cells from pancreatic ducts

A photomicrograph of a section through a human pancreas showing islets developing from ductal cells (neogenesis). The brown cells are (CK19-positive) epithelial cells lining the pancreatic ducts. The red stains insulin-positive cells. The image shows insulin-positive beta-cells developing from ductal epithelium. This is their normal origin in the foetus, and some further islet cells are produced in this way in the adult. In Type II diabetes there is no increase in cell mass in the islets, but there is an increase in beta-cell clusters.