Ovarian Cycle

ovarian cycle HORMONAL steps:

1. hypothalamus releases GnHR by anterior pituitary 2. this causes a release of FSH and LH 3. FSH develops granulosa cells during follicular phase during follicular phase. --> estrogen is released (FSH and LH are initially inhibited by estrogen but are then positively impacted as LH increases with increasing estrogen, however, inhibitin negatively impacts FSH) 4. increases LH levels induces ovulation as follicle become corpus luteum. high estrogen and progesterone are released which negatively feedbacks to GnHR and LH, FSH( in pregnancy the levels of those hormones would increase. ) 5. LH decreases and no more progesterone or estrogen is releases . and menstruation occurs.

follicular phase

The first phase of the ovarian cycle, during which a follicle (an oocyte and its surroudning cells) enlarges and matures. This phase is under the control of FSH from the anterior pituitary, and typically lasts from day 1 to day 14 of the menstrual cycle. The follicle secretes estrogen during this time period.

ovulatory phase

The second stage of the general menstrual cycle, when the ovum is released. triggered by LH. Remnants of follicle becomes corpus luteum.

luteal phase

The third phase of the ovarian cycle, during which a corpus luteum is formed from the remnants of the follicle that has ovulated its oocyte. The corpus luteum secretes progestrone and estrogen during this time period, which typically lasts from day 15 to day 28 of the menstrual cycle. Formation of the corpul luteum is triggered by the same LH surge that triggers ovulation, however in the absence of LH (levels quickly decline after the surge) the corpus luteum begins to degenerate.

structures of eggs

outer is the corona radiata and inner layer is the zona pellucida