Experimental ureterohydronephrosis in fetal rats.

This study tests the hypothesis that prenatal exposure to 2,4-dichlorophenyl-p-nitrophenyl ether (nitrofen), an herbicide known to induce pulmonary hypoplasia and other malformations in fetal rats, also may induce ureterohydronephrosis (UHN) and oligohydramnios. Time-dated pregnant Wistar rats were given 100 mg of the chemical on day 9 or 11 of gestation, and the findings in their fetuses were compared with those of suitable controls. Marked bilateral UHN was found in the majority of exposed fetuses, but without evidence of either mechanical obstruction or dysplastic parenchymal lesions. These animals had various degrees of lung hypoplasia. The amount of fluid in their amniotic sacs was increased rather than decreased and it was independent of lung weight but correlated to some extent with UHN grade. Urinary tract dilatation and polyhydramnios in this model most likely are attributable to polyuria caused by nitrofen-induced impairment of renal concentrating capacity. This relatively simple animal model might facilitate research into some aspects of the physiology of nonobstructive, prenatally dilated urinary tracts.