Once an oocyte is selected, the following steps lead to ovulation:
- The follicle that contains the oocyte starts to grow and mature under the influence of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) produced by the pituitary gland.
- The oocyte undergoes meiosis I and produces a secondary oocyte and a polar body.
- As the follicle continues to grow, it fills with fluid, and the pressure inside increases.
- At a certain point, usually around day 14 of a 28-day menstrual cycle, the follicle ruptures and releases the mature oocyte from the ovary. This process is known as ovulation.
- The released oocyte is swept up by the fimbriae of the fallopian tube and begins its journey towards the uterus.
- If the oocyte is fertilized by a sperm during its journey, it may implant in the uterine lining and develop into a fetus. If the oocyte is not fertilized, it will degenerate and be expelled from the body during menstruation.