Refractoriness to Ovarian Stimulation in the Rhesus Monkey

Abstract

Each of 5 immature [female] rhesus monkeys was injected daily with a highly purified gonad-stimulating hormone prepared from the serum of the pregnant mare. The period of injection varied from 45 to 70 days. Under the influence of the hormone, reddening of the sexual skin and great increase in the size of the follicles were observed; however, these criteria of ovarian stimulation disappeared during the time the hormone was being administered. Menstruation also occurred during this time and following the fading of the sexual skin and decrease in the size of the ovaries. Injection of the serum, obtained from the monkeys at the time the ovaries had regressed, into immature rats together with the gonadotropic hormone completely inhibited the action of the hormone. The amt. of serum required for this antagonistic action was small. Serum obtained from the same monkeys before the injection of the hormone was without antagonistic action when tested in the immature rat. An apparent refractory condition of the ovaries of the immature monkeys was produced by chronic treatment with the purified hormone. This condition is believed to be related to the presence of a substance in the serum which prevents the continued action of the hormone on the ovaries of the monkey.