Summary of female reproductive cycle days 1-28

Показать описание

Follow us:

■ The first five days of the cycle include the menstrual phase.
■ Progesterone and estrogen levels are low.
■ Menses occurs.
■ GnRH pulses more frequently promoting FSH and LH levels to rise.
■ Primary follicles are stimulated to develop.
■ Days five through thirteen consist of the preovulatory ovarian phase and the proliferative uterine phase.
• Simultaneously, the production of estrogen increases, stimulating further follicular maturation.
• Endometrial cells proliferate, thereby doubling the thickness of the endometrium.
■ Rising estrogen levels stimulate increased pulsing of GnRH and increased secretion of FSH and LH (positive feedback loop with estrogen).
■ Primary oocyte undergoes meiosis to form secondary oocyte.
• Estrogen levels peak causing an LH surge.
■ LH stimulates the mature follicle to rupture and release the secondary oocyte.
• Days 15-28 include the postovulatory ovarian phase and the secretory uterine phase.
■ The collapsed follicle becomes the corpus luteum, secreting greater amounts of progesterone, estrogen, and inhibin.
■ increased ovarian hormones, especially progesterone, promote endometrial proliferation and secretion.
• Endometrial glands secrete glycogen preparing for implantation of an embryo.
• Higher levels of inhibin stop the formation of LH and FSH by the anterior pituitary.
• If the secondary oocyte is not fertilized, the corpus luteum degenerates and cycle begins again.