It is the long range plan of this research project to study steroid metabolism and steroid binding in target tissues with emphasis on effects of hormonally-active xenobiotics. The studies will include the characterization of cytoplasmic and nuclear receptors in developing tissues of normal and abnormal animals. We also plan to study placental transfer and placental and fetal uptake and retention of hormonally-active xenobiotics. Recent emphasis has involved the perinatal development of steroid conjugation in rodents and the ontogeny of steroid cytoplasmic and nuclear receptors in target tissues in relation to gestational exposures to diethylstilbestrol and 2,3,7,8-tetrachlorodibenzo-p-dioxin.