Which hormone is secreted by the anterior pituitary gland that initiates follicle maturation?

The hormone that initiates follicle maturation and is secreted by the anterior pituitary gland is follicle-stimulating hormone (FSH). FSH plays a crucial role in the reproductive system, particularly in both males and females. In females, FSH promotes the growth and maturation of ovarian follicles, which contain the eggs. It stimulates the granulosa cells in the follicles to produce estrogen, a hormone that is vital for the regulation of the menstrual cycle and for the development of secondary sexual characteristics.

In males, FSH is important for the production of sperm, working in conjunction with testosterone to support the process of spermatogenesis in the testes. The secretion of FSH is regulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus, and its levels fluctuate throughout the menstrual cycle in females, reflecting its role in follicular development.

Other hormones mentioned play different roles: luteinizing hormone (LH) also influences ovarian and testicular function but primarily triggers ovulation and testosterone production, while estrogen and progesterone are involved in preparing the uterine lining for implantation and maintaining pregnancy, respectively. Thus, FSH's specific role in follicle maturation sets it apart as the correct answer.