During development, 17alpha-estradiol is a potent estrogen and carcinogen.

Neonatal administration of estradiol-17beta (E2-17beta) increases the nuclear DNA content in the mouse reproductive tract. Similar responses have been demonstrated for synthetic estrogens such as diethylstilbestrol. One of the questions raised regarding environmental estrogens such as organochlorines is whether they are potent enough to result in abnormal changes such as those demonstrated by both natural and synthetic estrogens. To test this hypothesis, female BALB/c mice were treated neonatally (days 1-5) with either E2-17beta or estradiol-17alpha (E2-17alpha), an inactive stereoisomer in adult reproductive tissues. We also proposed whether neonatal administration of (E2-17alpha) was tumorigenic and whether the effects were age dependent. To answer these questions, one set each of 10 day-old treated and control mice received short-term secondary administration of E2-17beta, E2-17alpha, or cholesterol. Cervicovaginal tracts from intact BALB/c mice were examined histologically and by flow cytometry at 70 ...