Ultrastructural analysis of pancreatic carcinogenesis. IV. Pseudoductular transformation of acini in the hamster pancreas during N-nitroso-bis(2-hydroxypropyl)amine carcinogenesis.

Electron and high resolution light microscope studies were made of the pseudoductular structures that develop in the pancreas of the Syrian hamster during chronic treatment with the pancreatocarcinogen, N-nitroso-bis(2-hydroxypropyl)amine (BHP). These pseudoductules, which precede the development of tumours, arise from acini, whose cells undergo dedifferentiation by selective autophagy of their zymogen granules and granular endoplasmic reticulum. It is proposed that the pseudoductules develop into the ultrastructurally similar cystic foci that appear to be the immediate precursors of pancreatic tumours in this experimental model. The possibility is discussed that the acinar cells are the primary target for BHP carcinogenesis.