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How does follicle-stimulating hormone affect the ovaries?

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Detailed cross-sectional illustration of a human ovary showing the stages of follicle development, ovulation, and corpus luteum formation, with labeled structures including primordial, primary, secondary, and mature follicles, a ruptured follicle releasing an ovum, and corpus luteum and albicans. An inset at the bottom shows the ovary's location in the female reproductive system. — ovary The steps of ovulation, beginning with a dormant primordial follicle that grows and matures and is eventually released from the ovary into the fallopian tube.

Follicle-stimulating hormone (FSH) is a gonadotropic hormone secreted by the pituitary gland that plays a critical role in the regulation of the ovary.12

In the female reproductive system, FSH is essential for the menstrual cycle and monthly ovulation. Its primary effects on the ovaries include:1

Follicular Development: FSH stimulates the growth and maturation of ovarian follicles, which are small, egg-containing vesicles. At the beginning of the menstrual cycle, an increase in FSH secretion triggers several follicles to enlarge and migrate toward the outer surface of the ovary.123
Hormonal Regulation: By promoting the development of these follicles, FSH facilitates the production of estrogens (such as estradiol) by the follicular cells.23
Synergy with LH: FSH operates in conjunction with luteinizing hormone (LH). While FSH initiates the maturation process, the subsequent rise in LH—triggered by increasing estrogen levels—eventually leads to the rupture of the mature Graafian follicle and the release of the egg.13

Through this rhythmic, cyclical activity, FSH ensures the ongoing maturation of follicles necessary for reproductive function.13