Effects of ddt homologs administered to female rats during the perinatal period.

The administration of estrogen to female rats during the perinatal period induces a masculine pattern of hypothalamic differentiation resulting in persistent vaginal estrus (PVE) and anovulation. 10 mg day of the estrogenic homologs o,p-DDT, o,p-DDE, and dda, as well as allegedly nonestrogenic forms of the pesticide, p,p-DDT and o,p-DDD, were given by gavage from days 15-19 of pregnancy. 1-mg doses of the homologs were also given SQ daily to female rats on the second, third, and fourth days of life. Vaginal opening was delayed by 2 days in rats derived from the dams gavaged with o,p-DDD. Periodic examination of estrous cycles in the rats treated neonatally with o,p-DDD revealed PVE by 209 days of age, and absence of corpora lutea by 258 days of age. Prior to 4 months of age, estrous cycles were normal in these animals. The remaining pesticide homologs tested, regardless of the mode of administration, had no significant effect on the estrous cycles or on endocrine gland weights.