An in vitro model of pancreatic carcinoma. Morphology and in vivo growth.

Pancreas rudiments from 13-day rat embryos were cultured in the presence of dimethylnitrosamine (DMN) for up to 10 weeks. Pancreas morphogenesis and differentiation occurred during the first week of culture. Acinar cell degeneration and necrosis began on the fifth day of culture and resulted in almost complete loss of acinar cells, islet cells, and fibroblasts by the end of the third week. This was associated with proliferation of cells without zymogen granules (centroacinar, ductal, or undifferentiated?). Theses cells formed glandular structures which extended to the surface of the explant. By the end of the fourth week, explants resembled ductal hyperplasia with foci of carcinoma in situ. The distribution pattern of neoplasia in 343 explants examined after 10 weeks of DMN treatment was as follows: 79% resembled ductal cell carcinoma; 9%, ductal hyperplasia; and 3%, acinar cell carcinoma. Nude mice injected with cell suspensions prepared from 10-week-old culture developed subcutaneous nodules. These nodules resembled duct cell carcinoma with desmoplastic reaction.