Cytological studies of carcinogen-treated bovine pancreatic ductal organ explants.

In order to develop a model to study cytological alterations in human pancreatic cancer, we have exposed bovine pancreatic ductal organ explants to a single dose of 2.5 micrograms per ml of N-methyl-N-nitroso-N'- nitroguanidine (MNNG). At serial time intervals, contact cytology smears of the explants were prepared and stained with the Papanicolaou stain. Control samples contained classic tall columnar and cuboidal ductal cells. Cells were uniform in size, shape, staining characteristics, and nuclear morphology. Ductal explants exposed to MNNG progressed through a series of dysplastic and atypical stages during the first 5 to 12 days in culture. Chromatin became increasingly more granular and nucleoli increased in both number and size. Exposed cells were larger than controls and had many dysplastic features. From day 15 to 30, the cells underwent changes morphologically consistent with those of human pancreatic adenocarcinomas .