oestrogens

Steroid sex hormones, derived from cholesterol, which are produced mainly in the ovaries and placenta. This group of hormones, which includes oestradiol (the most active female hormone), oestriol, and oestrone, not only promote maturation of the female reproductive system but are important for controlling the menstrual cycle, production of ova, and maintenance of pregnancy.

— Saffron A. Whitehead

See sex hormones; steroids.

The female sex hormones; chemically they are steroids, although non-steroidal compounds also have oestrogen activity, including the synthetic compounds stilboestrol and hexoestrol. These have been used for chemical caponization of cockerels and to increase the growth rate of cattle. See also capon.

Compounds with oestrogenic activity are found in a variety of plants; collectively these are known as phytoestrogens.