What hormones control the follicular phase in the ovarian cycle?

The follicular phase of the ovarian cycle is primarily controlled by follicle-stimulating hormone (FSH). During this phase, FSH is released from the anterior pituitary gland in response to signals from the hypothalamus. Its primary role is to stimulate the growth and maturation of ovarian follicles, which are fluid-filled sacs containing developing eggs. As these follicles grow, they produce estrogen, which plays a significant role in the regulation of the menstrual cycle and prepares the endometrium for potential implantation.

While estrogen is also crucial in the ovarian cycle, it acts more as a feedback signal that influences the release of hormones rather than being a primary driver of the phase. Luteinizing hormone (LH) becomes more prominent later in the cycle, particularly during the ovulatory phase. Progesterone is primarily involved in the luteal phase that follows ovulation, where it works to maintain the uterine lining for a potential pregnancy.

Therefore, follicle-stimulating hormone is correctly identified as the hormone that primarily controls the follicular phase by promoting the development of ovarian follicles and facilitating the production of estrogen.