Figure 2: Sources of the sex steroids in young men and women. Sex hormones are produced by the gonads, the adrenals, and by peripheral tissues. The ovary, adrenal gland, and testis are shown at the top of the chart. The white box in the central field denotes the circulatory compartment. The left side of the circulatory compartment below the ovary shows circulating levels of the sex hormones in young women; the right side of the circulatory compartment, below the testis, shows circulating levels of sex hormones in young men. The gray box with a bold border below the adrenal gland denotes the peripheral tissue compartment and illustrates peripheral conversion of the adrenal prohormone, DHEA, to sex hormones. Bold arrows denote primary sources of the sex hormones. The ovaries and testes are primary sources of circulating estradiol and testosterone in young women and men, respectively. The peripheral tissues (mainly adipose tissue) are a primary source of circulating estradiol in men and of estrone in both sexes. DHEA: dehydroepiandrosterone; ADIONE: androstenedione; ADIOL: androstenediol; DHT: dihydrotestosterone; E2: estradiol; E1: estrone