Pancreas cells, coloured scanning electron micrograph (SEM). The small sections seen here are clusters of acini cells. These are exocrine cells, secreting digestive enzymes. The enzymes drain into a highly branched system of ducts of increasing size, that terminates in the main pancreatic duct, which feeds into the duodenum (small intestine). The other function of the pancreas is the endocrinal secretion of hormones, in particular insulin.