Sequential alteration of the pancreas during carcinogenesis in Syrian hamsters by N-nitrosobis(2-oxopropyl)amine.

A systematic histological-pancreatographic study indicated that, during pancreatic carcinogenesis by N-nitrosobis(2-oxopropyl)amine, the ductular cells (cells of intercalated or intralobular ductules and especially those of peri-and intrainsular ductules) are most responsive. The initial proliferation (multiplication) and distension of ductules seemed due to primary hyperplasia of ductular cells, followed by metaplasia, atypia, and malignant alteration. Among 75 induced adenocarcinomas, most were of ductular origin, whereas only a few seemed to arise from ductal epithelium (interlobular, secondary, and main ducts). There was no preferential segment for tumor development. However, about one-third of the adenocarcinomas in the head of the pancreas had a periampullary location, while most neoplasms in other pancreatic lobes arose along the main pancreatic ducts. There was evidence of "leaking" of pancreatic juice through altered epithelium of main ducts, and this may have caused a marked periductal chronic inflammatory reaction.