Effect of Single Injections of Estradiol Benzoate on the Normal Human Menstrual Cycle with Special Reference to the Problem of Estrogen Sensitivity

Despite the fact that estrogens are extensively used in clinical gynecology, from the literature available it appears that, with one exception (1), there is no information concerning the effect of estrogens on the human ovary. Even when estrogen has been used to postpone the onset of mestruation in normal women (2) it has not been possible to predicate how it was accomplished except that it is commonly stated that this hormone inhibits temporarily the gonadotropic function of the anterior lobe of the pituitary. The understanding of the action of estrogen in the human female is further complicated by the fact that even in laboratory mammals and especially in primates there is still a paucity of data as to how estrogen affects the normal ovary. According to Allen, Hisaw and Gardner (3) estrogens given over long periods of time inhibit the ovary. The ovaries of mice after treatment with 500 i.u. of estrogen weekly for 150 days are usually small (3).