The pancreas is divided into lobules by connective tissue septae. Lobules are composed largely of grape-like clusters of exocrine cells called acini, which secrete digestive enzymes. Exocrine secretions from acini flow successively through intercalated ducts, intralobular ducts, interlobular ducts and finally into the duodenum through the main pancreatic duct.
Embedded within the pancreatic exocrine tissue are Islets of Langerhans, the endocrine component of the pancreas. Islets contain several cell types and are richly vascularized.