The three naturally occuring oestrogens are oestradiol?, oestriol? and oestrone?. In the body these are all produced from androgens? through enzyme action. Oestradiol is produced from testosterone and oestrone? from androstenedione?. Oestrone is weaker than oestradiol, and in post-menopausal women more oestrone is present than oestradiol.
While oestrogens are present in both men and women, it is found in women in significantly higher quantities. It promotes the development of female secondary sexual characteristics, such as breasts.