Follicle-Stimulating Hormone (FSH) is a hormone produced by the pituitary gland in the brain. It plays a crucial role in regulating the reproductive processes in both men and women. In women, FSH stimulates the growth of ovarian follicles, which contain eggs, and is essential for the menstrual cycle. In men, FSH is important for the production of sperm. FSH levels fluctuate throughout the menstrual cycle and can be influenced by various factors, including age and health conditions. Abnormal levels of FSH can indicate issues with fertility or hormonal imbalances, making it an important marker in reproductive health assessments.