Gastric epithelial cell proliferation in monkeys fed 3,4,3',4'-tetrachlorobiphenyl.

Rhesus monkeys (Macaca mulatta) fed diets containing 1 or 3 mg/kg of 3,4,3',4'-tetrachlorobiphenyl (3,4-TCB), became moribund after 7-14 weeks. In the body of the stomach the mucosa was thick and cystic gastric glands penetrated the muscularis mucosae. The zymogenic and parietal cells were replaced by or converted into mucus-secreting cells. Autoradiographs of animals labelled with [3H]thymidine showed that in control monkeys gastric epithelial cell proliferation was limited to the isthmus and neck regions of the glands throughout the stomach. In the 3,4-TCB-fed animals most DNA synthesis also occurred in these regions, but [3H]thymidine labelled cells were also seen in the bases of the glands. The labelling indices were not elevated, and therefore the submucosal glands and cysts in this lesion may develop by a failure of the newly formed, downward migrating cells to differentiate and lose their proliferative capacity.