What occurs during the follicular phase of the ovarian cycle?

During the follicular phase of the ovarian cycle, the primary event is the maturation of ovarian follicles. This phase begins on the first day of menstruation and continues until ovulation. Under the influence of follicle-stimulating hormone (FSH), several follicles begin to mature in the ovaries. Typically, one dominant follicle will mature fully and eventually release an ovum during ovulation, which marks the end of the follicular phase.

The process involves the development of the ovarian follicles from primary follicles to secondary and tertiary follicles. As these follicles mature, they produce increasing amounts of estrogen, which plays a crucial role in preparing the endometrium for a potential pregnancy. At the end of this phase, only the dominant follicle is usually left, and it is the one that will be poised for ovulation.

This understanding illustrates why the option regarding multiple follicles maturing and one ovulating aligns with the biological processes occurring during this phase. The formation of the corpus luteum occurs in the subsequent luteal phase, thus making it an inappropriate answer in the context of the follicular phase. Similarly, claiming that no follicles mature or that the endometrium is shed does not accurately depict the physiological changes of the ovarian cycle during this specific phase.