Which hormone is primarily responsible for the regulation of the menstrual cycle?

• A. Testosterone
• B. Estrogen
• C. Progesterone
• D. Luteinizing hormone (LH)

Answer: (B)

Estrogen plays a pivotal role in regulating the menstrual cycle, primarily through its influence on the ovarian follicles and the uterine lining. During the follicular phase of the menstrual cycle, estrogen is secreted by the developing ovarian follicles, promoting the growth and maturation of the egg while also stimulating the thickening of the endometrial lining in preparation for a potential pregnancy. Elevated estrogen levels trigger the surge in luteinizing hormone (LH) that leads to ovulation.

Following ovulation, during the luteal phase, progesterone takes over to maintain the endometrium and prepare it for implantation. However, estrogen's role in the early part of the cycle and its contribution to the hormonal changes that regulate ovulation and menstruation supports its designation as the primary hormone involved in menstrual cycle regulation. This interconnectedness among hormones underscores the significance of estrogen in orchestrating the complex events of the menstrual cycle.