Reduced cell proliferation in fetal lung after maternal administration of pilocarpine: a scintillation autoradiographic study.

Fetuses were obtained on the 28th gestational day from pregnant New Zealand white rabbits treated daily, on the 24th through the 27th gestational day, with pilocarpine HCl, 5 mg/kg in saline, or saline alone. Lung fragments from these fetuses were incubated for two hours in medium containing 3H-thymidine. Scintillation autoradiography of 1-micrometer-thick sections of these fetal lungs revealed that the lung tissue from pilocarpine-treated fetuses had significantly lower labelled cell indices for both alveolar epithelial cells and interstitial cells. These results indicate that pilocarpine treatment promotes differentiation of immature cells in the fetal lung at the expense of cell proliferation.