The first half of the ovarian cycle is the follicular phase. Slowly rising levels of FSH cause the growth of follicles on the surface of the ovary. This process prepares the egg for ovulation. As the follicles grow, they begin releasing estrogen. Which phase of the ovarian cycle is characterized by the growth of follicles and the release of estrogen?
1) Follicular phase
2) Luteal phase
3) Menstrual phase
4) Ovulation phase