A hormone that stimulates or controls the development and maintenance of female sex characteristics in mammals by binding to oestrogen receptors. The oestrogens are named for their importance in the oestrous cycle. The oestrogens that occur naturally in the body, notably estrone, estradiol, estriol, and estetrol are steroids. Other compounds with oestrogenic activity are produced by plants (phytoestrogens) and fungi (mycoestrogens); synthetic compounds with oestrogenic activity are known as xenoestrogens.
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