THRESHOLD BLEEDING AND THE SEX SKIN IN THE CASTRATE FEMALE CHIMPANZEE1,2

Abstract

Cyclical genital activity in castrate 9 rodents and primates has been frequently observed in animals under treatment with constant dosage of sex hormones. In the chimpanzee, 2 external indicators of such activity are available, menstruation and variation in the sex skin. By choosing the proper unvarying dosage, it is possible to induce changes in both these indicators. Since these changes are not in phase it is not possible for the cyclical activity to be produced by alterations in level of endogenous sex hormones of adrenal or other origin. It is concluded that cyclical variations in threshold of the end-organs must be considered.