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Any of a class of hormones that primarily influence the female reproductive system's development, maturation, and function. The three major estrogensestradiol, estrone, and estriolare produced mainly by the ovaries and placenta; the adrenal glands and the testes secrete smaller amounts. Estrogens affect the ovaries, vagina, fallopian tubes, uterus, and mammary glands and play crucial roles in puberty, menstruation, pregnancy, and parturition (labour). They also influence the structural differences between female and male bodies. In experimental animals, loss of estrogens diminishes mating desires and other behavioral patterns.
This entry comes from Encyclopædia Britannica Concise. For the full entry on estrogen, visit Britannica.com.