Studies on pancreatic duct system. I) The fine structure of the major pancreatic ducts of normal and chronic pancreas injury dogs.

The major pancreatic ducts of normal dogs, and experimental dogs with chronic pancreas injury following adjuvant injection have been studied ultrastructurally and histochemically. The ducts are lined by a single layer of columnar epithelial cells. They possess many short microvilli with a fuzzy surface coat and apical sulfomucin droplets, suggesting that they are acting not only as a protective barrier, but also facilitating the transport of the pancreatic juice. Apart from these ordinary epithelial cells, multivesicular cells and some few endocrine cells have been detected between the duct epithelia. Because of a rich cellular network lining the major pancreatic ducts, it is hardly believed that they have no important function except for passive transport of pancreatic juice. In the diseased dogs, the lumina were irregularly dilated and the epithelial cells were flattened with the loss of microvilli. These changes may be a predisposition of inspissated secretion.