Endocrine systems and behavior

Abstract

Estradiol, either directly from the ovary of females or as a metabolite of testosterone from the testes of males, seems to be the necessary and probably sufficient endocrine signal for sexual differentiation and adult sexual expression. Progesterone, in females, may play an important priming or facilitative role prior to estrus, especially following pregnancy, when blood estrogen levels are high for a prolonged period. At high doses, progesterone clearly inhibits the expression of sexual behavior.