Estrogen

Estrogen or oestrogen is a group of female hormones.^[1] It includes oestrone (E1), oestradiol (E2), and oestriol (E3).

Oestradiol is the most important oestrogen. Oestrogen is mainly secreted by the ovary, a small amount by the liver, adrenal cortex, and breast. In pregnancy, the placenta can also have a lot of secretion. Male testes also secrete a small amount. Ovary mainly secretes β-estradiol, other estrogens are less important.^[2]

Oestrogen helps women grow during puberty and is part of the menstrual cycle. During menopause, oestrogen levels go down. The male hormone that is similar is androgen.

Biosynthesis

Steroidogenesis, showing estrogens at bottom right as in pink triangle^[3]

References

↑ The word comes from the Greek οἶστρος, meaning gadfly. Its use here is not literal.
↑ Whitehead S.A. & Nussey S. 2001. Endocrinology: an integrated approach. Oxford: BIOS. ISBN 1-85996-252-1
↑ Häggström M, Richfield D (2014). "Diagram of the pathways of human steroidogenesis". WikiJournal of Medicine. 1 (1). doi:10.15347/wjm/2014.005. ISSN 2002-4436.

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[1] The word comes from the Greek οἶστρος, meaning gadfly. Its use here is not literal.

[2] Whitehead S.A. & Nussey S. 2001. Endocrinology: an integrated approach. Oxford: BIOS. ISBN 1-85996-252-1

[HäggströmRichfield2014-3] Häggström M, Richfield D (2014). "Diagram of the pathways of human steroidogenesis". WikiJournal of Medicine. 1 (1). doi:10.15347/wjm/2014.005. ISSN 2002-4436.

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Human reproductive system
Female anatomy	Female reproductive system – Breasts – Cervix – Clitoris – Clitoral hood – Fallopian tubes – Bartholin's glands – Gräfenberg spot (G-spot) – Hymen – Labia – Ovaries – Skene's glands – Urethra – Uterus – Vagina – Vulva
Female physiology	Menstruation – Pregnancy – Childbirth – Lactation – Estrogen – Orgasm – Ovum
Male anatomy	Male reproductive system – Bulbourethral glands – Corpus cavernosum – Ejaculatory ducts – Epididymis – Foreskin – Frenulum – Glans penis – Penis – Prostate – Rete testis – Scrotum – Seminal vesicles – Seminiferous tubules – Sertoli cell – Spermatic cord – Testicles (testes) – Urethra – Vasa deferentia
Male physiology	Ejaculation – Erection – Orgasm – Semen – Sperm – Testosterone
Anatomy is the study of the parts of the body • Physiology is the study of how the body works