THE QUANTITATIVE ASSAY OF “FOLLICLE STIMULATING” SUBSTANCES1

Abstract

A number of the responses elicited in immature female rats and mice by gonadotropic extracts prepared from various sources have been applied to the quantitative assay of these extracts. The production of follicular enlargement, luteinization, ‘blood point’ formation, increase in ovarian weight, precocious vaginal canalization and induction of estrus as judged by the vaginal smear have all been used, singly or in combination, as indicators of the gonadotropic potency of the injected material. At the inception of our work on the concentration and purification of the urinary gonadotropic material of ovariectomized and post-menopausal women, it became imperative to assay our preparations as accurately as possible. Earlier work (1) demonstrated that this gonadotropin is predominantly follicle-stimulating in nature, thus precluding the possibility of using luteinization or hemorrhagic follicle formation as a criterion of activity. Attempts were therefore made to assay the preparations, using immature mice, on the basis of follicular enlargement, increase in ovarian weight and vaginal canalization. In addition, since the uteri of the test animals were much enlarged in every positive test, this organ was routinely weighed.