Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) play important roles in both male and female reproductive processes. Because these hormones work so closely together, you may find it difficult to see the differences between them. But each hormone in the human body has a distinct purpose; each one is unique.
FSH and Its Purpose
Follicle-stimulating hormone (FSH) is a protein hormone responsible for stimulating the production of eggs in the ovary or sperm in the testes. It's produced in the anterior pituitary gland. This is a small gland located in the hypothalamus, an important portion of the lower brain that deals with the endocrine and nervous systems. FSH plays a key role in the follicular phase of the female reproductive cycle. This is the first phase of the cycle, during which follicles form in the ovaries. These follicles contain eggs. When the pituitary gland is stimulated by gonadotropin-releasing hormone (GnRH) to secrete FSH during the follicular phase, it attaches to receptors on the follicles, stimulating growth and the release of estrogen. This is important, because it helps the body reach ovulation. In male reproduction, FSH and testosterone work together to produce sperm.
LH and Its Purpose
Luteinizing hormone (LH) is also produced in the anterior pituitary gland. It, too, plays a large role in the female reproductive cycle. As the follicles in the ovary near full growth, they begin to secrete large quantities of estrogen. This stimulates heightened production of GnRH in the hypothalamus, which in turn stimulates heightened production of both FSH and LH -- particularly LH. By this time, the follicles have developed LH receptors, and are now able to respond to the hormonal surge. Ovulation occurs about a day after the LH surge. The role of LH doesn't end with ovulation, however. During the luteal phase that follows, the LH triggers the remaining follicular tissue in the ovary to form a glandular structure called the corpus luteum, which slowly disintegrates, allowing the cycle to begin anew. In males, LH stimulates the Leydig cells in the testes to produce testosterone, which in turn works with FSH to produce sperm.
Telling Them Apart
While FSH and LH may seem similar due to their complementary roles, they are actually unique from each other. In the male reproductive system, FSH's role cannot be completed without LH. In the female reproductive cycle, they have overlapping but separate functions. When the follicles accept hormonal cues from FSH, they have no LH receptors. By the time they are prepared for LH, the FSH receptors are gone. Their names give away the differences in their roles, if it's hard for you to remember.
Tags: female reproductive, female reproductive cycle, pituitary gland, reproductive cycle, anterior pituitary, anterior pituitary gland