n.
Any of a class of hormones that primarily influence the female reproductive system 's development, maturation, and function.
The three major estrogens
estradiol, estrone, and estriol
are produced mainly by the ovaries and placenta ; the adrenal gland s and the testes secrete smaller amounts. Estrogens affect the ovaries, vagina , fallopian tubes, uterus , and mammary gland s 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.