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Ovarian follicle development
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In the ovary, an egg is not floating loose: it sits inside a small sac of cells called a follicle. The process by which that follicle matures until it can release the egg is called folliculogenesis, and it is extremely slow. It begins while a woman is still in her mother's womb, and each follicle takes about a year to be ready.
The process has two stages. In the first, the egg gets bigger, the cells around it .. the granulosa .. multiply and start making receptors for FSH, follicle-stimulating hormone. Another layer forms around them, the theca interna, which makes receptors for LH, luteinizing hormone. A receptor is the antenna a cell uses to hear a hormone: without it, the hormone goes right past.
In the second stage those antennas finally matter. FSH causes a fluid-filled space to open inside the follicle, the antrum. LH pushes the theca interna to make androgens, and an enzyme called aromatase can turn them into estrogen.
Several follicles start growing each month, but only one becomes the dominant one, the one that will ovulate. The smaller ones fall behind because they lose their sensitivity to FSH, and they end up degenerating.
In brief
Folliculogenesis is the maturation of an ovarian follicle; it starts before birth and takes about a year.
It has two phases. In the first, the oocyte grows, the granulosa expresses FSH receptors and the theca interna expresses LH receptors.
Then FSH takes over: a fluid-filled antrum opens, LH drives androgen production in the theca, and aromatase can turn those androgens into estrogen.
Only one becomes dominant; the small ones degenerate as they lose FSH sensitivity.
Out of the whole batch that month, one keeps the signal.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingEmbryology, Ovarian Follicle Development, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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