Table 1.
Main hormonal events during the ovulatory cycle, ordered chronologically
| Hormonal event | |
| 1 | An increase in FSH levels leads to recruitment and development of ovarian follicles. |
| 2 | Selected follicles produce rising estradiol levels. |
| 3 | Estradiol together with inhibin exerts a negative feedback upon the HHG axis, thus decreasing FSH levels. Estradiol also causes a negative feedback upon the kisspeptinergic neurons. |
| 4 | One of the selected ovarian follicles becomes dominant. Increasing high levels of estradiol change the negative feedback upon the hypothalamus and hypophysis to a positive one, which causes the midcycle gonadotrophin surge. |
| 5 | LH surge is initiated, which causes follicular luteinization and an initial progesterone rise. Progesterone maintains the LH peak and is necessary for follicular rupture and adequate ovulation. |
| 6 | Ovulation |
| 7 | LH and progesterone release pattern help in the formation and support of the corpus luteum. The corpus luteum secretes progesterone and estrogens. |
| 8 | If fertilization does not occur, the corpus luteum will start to regress after 6 days and will last for 11 to 17 days. |
| 9 | Estradiol and progesterone concentrations drop, which eliminates the negative feedback exerted upon the HHG axis. |
| 10 | A new cycle begins. |