9309422 Fadem Sex differences in reproductive behavior in mammals are determined not only by the genes and by hormones produced in adulthood, but also by steroid hormones secreted by the gonads during perinatal development. Although it is known that testicular androgens play an important role during perinatal development, androgens are metabolized into estrogens within CNS target cells. Determining whether an androgen or its estrogenic metabolite is the differentiating hormone is complicated since placental mammalian fetuses have systems which actually "protect" them from maternal estrogen. Thus, getting estrogen to the fetus and quantifying the amount of estrogen acting on the fetus is extremely important yet almost impossible to achieve. Dr. Fadem has developed a marsupial model to examine the role of estrogen. The newborns are born at a developmental stage equivalent to that of a 13-day fetal rat or 8-week human embryo. Hence, much of the fetal development occurs outside the body of the mother, making the fetal environment accessible in these mammals. Dr. Fadem will manipulate the hormonal environment of the newborn marsupials. She will assess the effects of these early manipulations on reproductive and aggressive behavior, morphology and physiology in adulthood. The results from these studies will contribute to a better understanding of various human disorders that result from insufficient or excess hormone exposure during sexual differentiation. ***
