Estrogen:Afemalesteroidhormonethat is produced by the ovaries and,inlesser amounts, by theadrenal cortex,placenta, andmaletestes.Estrogenhelpscontroland guide sexualdevelopment, including the physical changes associated with puberty. It also influences the course ofovulationin the monthly menstrual cycle,lactationafter pregnancy, aspects of mood, and the agingprocess. Production of estrogen changes naturally over the female lifespan, reaching adult levels with theonsetof puberty (menarche) and decreasing in middle age until the onset of menopause. Estrogen deficiency can lead to lack of menstruation (amenorrhea), persistent difficulties associated withmenopause(such as mood swings and vaginal dryness), and osteoporosis in older age. In cases of estrogen deficiency, natural and synthetic estrogen preparations may be prescribed. Estrogen is also a component of manyoralcontraceptives. An overabundance of estrogen in men causes development of female secondary sexual characteristics (feminization), such as enlargement ofbreast组织.
