What characterizes the follicular phase of the menstrual cycle?

The follicular phase of the menstrual cycle is characterized by the growth of ovarian follicles. During this phase, which begins on the first day of menstruation and lasts until ovulation, the pituitary gland releases follicle-stimulating hormone (FSH). This hormone stimulates the growth and maturation of ovarian follicles, each containing an egg. As the follicles develop, they produce estrogen, which helps prepare the uterine lining for a potential pregnancy.

In this phase, the focus is on the development of the follicles, which is fundamental for ovulation to occur later on. Once a dominant follicle matures, it will eventually lead to ovulation, but this is not a characteristic of the follicular phase itself—rather, it is a subsequent event that follows the completion of this phase. High progesterone levels are not noted during the follicular phase, as progesterone increases primarily after ovulation during the luteal phase. Therefore, the hallmark of the follicular phase is indeed the growth of ovarian follicles, making it the correct characterization of this part of the menstrual cycle.