Follicle-Stimulating Hormone (FSH) stimulates the growth of multiple follicles in the ovary.
• These developing follicles produce estrogen and inhibin B, which negatively feedback to decrease FSH secretion.
• This FSH drop causes atresia of most follicles except the dominant follicle.
————————————————
Why does the dominant follicle survive?
The dominant follicle survives and continues to grow even when FSH levels fall. This is due to 4 key reasons:
1. Increaseda FSH Receptor Sensitivity
• The dominant follicle has more FSH receptors than the others.
• This means it can respond to lower levels of FSH, unlike the other follicles.
2. Autocrine and Paracrine Support
• The dominant follicle begins to secrete local growth factors (like IGF-1, estradiol) that help maintain its own growth and inhibit atresia.
• These are autocrine/paracrine survival signals.
3. Better Blood Supply
• It develops a better vascular supply, ensuring more efficient delivery of hormones and nutrients, especially the remaining FSH.
4. Estrogen Production
• The dominant follicle produces the most estradiol, which continues the negative feedback loop to suppress FSH, further disadvantaging other follicles.
• In a way, it “kills the competition” by suppressing FSH that others need.
—————————————————
So, the dominant follicle survives FSH drop because it:
• Has more FSH receptors → more sensitive
• Secretes growth-promoting local factors
• Has better blood flow
• Outproduces estrogen, which suppresses FSH further, pushing others into atresia