Estrogenhormone. They are produced primarily by developing
follicles in the ovaries, the corpus luteum and the placenta.
Some estrogens are also produced in the adrenals and the
breasts, especially in post-menopausal women. The three
naturally occurring estrogens are estradiol (estradiol), estriol
(estriol) and estrone (estrone). In the body these are all
produced from androgens through enzyme action. Estradiol is
produced from testosterone and estrone from androstenedione.
Estrone is weaker than estradiol, and in post-menopausal women
more estrone is present than estradiol. While estrogens are
present in both men and women, it is found in women in
significantly higher quantities. They promote the development of
female secondary sexual characteristics, such as breasts, and
are also involved in controlling the menstrual cycle, which is
why most birth control pills contain estrogens. - Barbara
Seaman, "The Greatest Experiment Ever Performed on Women:
Exploding the Estrogen Myth'', Hyperion Press, 2003, hardcove