What is Follicle-Stimulating Hormone?

Follicle-stimulating hormone (FSH) is a glycoprotein hormone that plays a crucial role in regulating the female menstrual cycle and the male reproductive system. FSH is produced and secreted by the anterior pituitary gland, and it acts on the gonads (ovaries in females, testes in males) to regulate the production and maturation of gametes (eggs in females, sperm in males).

In females, FSH stimulates the growth and development of follicles in the ovaries. The follicles contain eggs, and as they mature, they release increasing amounts of estrogen. The increase in estrogen levels triggers a surge in luteinizing hormone (LH) secretion, which in turn triggers ovulation.

In males, FSH acts on the testes to stimulate the production of sperm. It does so by promoting the growth and maturation of the Sertoli cells, which are important for the production and maturation of sperm. FSH also stimulates the production of inhibin, a hormone that acts to regulate the secretion of FSH.

The levels of FSH in the blood are regulated by a feedback mechanism involving gonadal steroids (estrogens in females, androgens in males) and gonadotropin-releasing hormone (GnRH) produced by the hypothalamus. High levels of gonadal steroids inhibit the secretion of GnRH, which in turn decreases the secretion of FSH and LH. Low levels of gonadal steroids stimulate the secretion of GnRH, which increases the secretion of FSH and LH.

FSH levels can be measured through a blood test, and elevated levels of FSH can indicate a number of conditions, including infertility, menopause, primary ovarian insufficiency, and pituitary tumors. In females, elevated FSH levels can indicate a decline in ovarian function and a decreased ability to produce eggs. In males, elevated FSH levels can indicate a decline in testicular function and a decreased ability to produce sperm.

In infertility treatment, FSH is often used in combination with other hormones, such as human chorionic gonadotropin (hCG) and LH, to stimulate ovulation and increase the chances of pregnancy. In vitro fertilization (IVF) is a common procedure that involves the stimulation of follicle growth with FSH and the subsequent retrieval of eggs from the ovaries.

FSH deficiency is a rare condition that can occur due to problems with the pituitary gland or hypothalamus. In females, FSH deficiency can lead to a lack of menstrual periods and infertility, while in males it can lead to decreased testicular function and infertility.

In conclusion, FSH is a crucial hormone that plays an important role in regulating the female menstrual cycle and the male reproductive system. Its levels are regulated by a feedback mechanism involving gonadal steroids and GnRH, and elevated levels of FSH can indicate a number of conditions, including infertility and menopause. In infertility treatment, FSH is often used to stimulate ovulation and increase the chances of pregnancy. Deficiency of FSH can lead to infertility and decreased reproductive function in both females and males.