SENSITIVITY TO ESTROGEN STUDIED BY MEANS OF EXPERIMENTALLY INDUCED MATING RESPONSES IN THE FEMALE GUINEA PIG AND RAT1

IT IS GENERALLY RECOGNIZED that the response of an organism to estrogenic treatment is influenced not only by the quality and quantity of the substance used but also by the sensitivity or threshold to the hormone. Coward and Burn (I), Marrian and Parkes (2), and D'Amour and Gustavson (3) postulate that differences in the extent of the vaginal reaction to equal doses of estrogen are attributable toindividual differences in sensitivity. The importance of age in the degree of response to estrogenic treatment is apparent from the observation (4) that the menstrual thresh-old to ovarian follicular hormone is high in immature rhesus monkeys and from the observation (5) that the responsiveness of the perineum in adult baboons is more marked than in prepuberal animals Wiesner (6) states that, due to the absence of reactivity to estrogen, cornification of the vagina and enlargement of the uterus are not detectable within the first few days of postnatal life