Ovarian follicles up to ovulation
The ovaries contain eggs stored in small pockets called follicles. A follicle is an egg cell surrounded by a layer of cells involved in egg maturation. These ovarian follicles are formed in the woman's body before birth.
Following puberty, every month, approximately 12 to 14 days after the first day of menstruation in a "typical" monthly cycle, one of these follicles reaches maturity and is released into the uterine tube in a process called ovulation.
Ovarian follicles following ovulation
After ovulation, changes continue to take place in the ovaries. The remaining follicular cells undergo structural and biochemical changes. They develop into the corpus luteum.
While the ovarian follicles produced estrogen, the corpus luteum produce both estrogen and progesterone.