Oestrogen Production: The Primary Organ Oestrogen, a key female sex hormone (also spelled estrogen), is primarily produced in the ovaries.

Main Production Site

The ovaries serve as the chief organ for oestrogen synthesis in premenopausal women, with granulosa cells in ovarian follicles converting precursors like androstenedione into oestradiol, the most potent form. This process relies on follicle-stimulating hormone (FSH) to drive production in structures like the corpora lutea. During pregnancy, the placenta takes over as a major source.

Secondary Sources

Smaller amounts arise from extragonadal tissues including adipose (fat) tissue, adrenal glands, skin, brain, liver, and breasts, especially post- menopause when ovarian output drops. For instance, brain cells can synthesize oestrogen from cholesterol using local enzymes.

Key Facts in Brief

  • Primary organ : Ovaries (premenopausal females).
  • Potent form : Oestradiol (E2), alongside estrone (E1) and estriol (E3).
  • Two-cell model : Theca cells provide androgens; granulosa cells aromatize them to oestrogens.

TL;DR : The ovaries are the main organ where oestrogen is made.

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