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Follicles - Anatomy & Physiology (view source)
Revision as of 13:50, 9 September 2008
, 13:50, 9 September 2008no edit summary
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=== The Follicular Wave ===
* At the beginning of each cycle, a few primary follicles begin to develop into antral follicles.
* What causes the selection of particular follicles is unknown, but it is thought to be due to the paracrine action of growth factors such as EGF and IGFs.
* Major enlargement of the follicle is not due to the oocyte increasing in size, but down to the gain in follicular fluid secreted by the granulosa cells.
* A further selection process occurs whereby a single follicle (the dominant follicle) is selected for continued development.
* What causes this single follicle to be chosen is unknown.
* For complete follicular development to occur at this stage, LH and FSH are essential. The development of a tertiary follicle cannot happen in the absence of these gonadotrophins.
* The rest of the follicles which had started to enlarge undergo a degenerative process called atresia.
* The dominant follicle enlarges, mainly as a result of its expanding antrum.
* Growth of the dominant follicle is dependent on LH as the granulosa cells acquire LH receptors.
* Ovulation occurs in response to a dramatic increase in LH levels.
* The role of FSH is superceeded by LH in the dominant follicle.