Estrone (Standard) is the standard substance of Estrone, and it is applicable for quantitative analysis, quality control, and related research in biochemical experiments. Estrone (Aquacrine) is an aromatized C18 steroid with a 3-hydroxyl group and a 17-ketone, a major mammalian estrogen. It is converted from ANDROSTENEDIONE directly, or from TESTOSTERONE via ESTRADIOL. In humans, it is produced primarily by the cyclic ovaries, PLACENTA, and the ADIPOSE TISSUE of men and postmenopausal women.