PITUITARY-G0NAD INTERACTION IN IMMATURE FEMALE PARABIOTIC RATS1

Abstract

The pituitary gland of ovariectomized [female] rats in parabiosis with a normal [female] has a greater gonado-tropic activity and is more basophilic than the pituitary of a single intact [female], but has less activity and fewer basophils than a single ovariectomized [female]. The pituitary gland of the intact parabiont in which excessive ovarian hypertrophy occurs has the lowest gonadotrophic activity and the smallest number of chromophils. Injn. of small doses of estradiol reduces the percentage of basophils in the pituitary gland of ovariectomized parabiotic and single rats, and at the same time increases the number of acidophils. The gonadotrophic content of the pituitary glands of these rats is greater than that of similar non-injected animals. These observations provide the basis for the following hypotheses: 1) FSH is produced by the basophils and LH by the acidophils of the pituitary gland, 2) the differentiation of each type of chromo-phil from chromophobes is controlled by the level of blood, estrogen, and 3) the rate at which the chromophils release their gonadotrophin is dependent upon the level of blood FSH and LH.