Difference Between FSH and LH

The main difference between FSH and LH is that FSH stimulates the growth and maturation of ovarian follicle whereas LH triggers ovulation in females. Furthermore, FSH stimulates spermatogenesis while LH stimulates the production of testosterone in males.

FSH (follicle-stimulating hormone) and LH (luteinizing hormone) are two hormones secreted by the anterior pituitary. Since they stimulate gonads in both females and males, they are commonly called gonadotrophins.

Key Areas Covered

1. What is FSH
     – Definition, Role, Regulation
2. What is LH
     – Definition, Role, Regulation
3. What are the Similarities Between FSH and LH
     – Outline of Common Features
4. What is the Difference Between FSH and LH
     – Comparison of Key Differences

Key Terms

FSH (Follicle-Stimulating Hormone), Gonadotrophins, LH (Luteinizing Hormone), Ovarian Follicle, Ovulation

What is FSH

FSH is a type of gonadotropin, which regulates the functions of ovaries and testes. It stimulates the growth of the ovarian follicle in females. This hormone also stimulates the production of steroids by the ovary; estradiol is produced during the follicular phase while progesterone is produced during the luteal phase. On the other hand, in the middle of the menstrual cycle, FS, along with LH, triggers ovulation. In males, FSH stimulates Sertoli cells of the testicles to produce an androgen-binding protein (ABP), which stimulates spermatogenesis. Also, it is an essential hormone in the pubertal development of gonads.   

Figure 1: FSH and LH Levels During Menstrual Cycle

The production of FSH is regulated by the number of hormones secreted by ovaries and testes through a system called hypothalamic-pituitary-gonadal axis. Thus, the hypothalamus releases gonadotropin-releasing hormone (GnRH), which stimulates the release of FSH from the anterior pituitary. Besides, the elevated levels of FSH in the bloodstream stimulates the production of inhibin by gonads, which in turn decreases the secretion of FSH from the anterior pituitary through negative feedback loops.

What is LH

LH is the other type of gonadotrophin released by the anterior pituitary gland, regulating the functioning of the gonads. The main function of LH in females is to trigger ovulation along with FSH. LH is especially responsible for the development of the follicle into corpus luteum, initiating ovulation. Also, during the first two weeks of the menstrual cycle, LH stimulates the ovary to produce estradiol. During the last two weeks of the menstrual cycle, it stimulates the production of progesterone by the corpus luteum, which supports the early stages of pregnancy.

Figure 2: FSH and LH Function

In males, LH stimulates Leydig cells in testicles to produce testosterone. The elevated levels of testosterone in the bloodstream inhibit the release of LH by the anterior pituitary.

Similarities Between FSH and LH

• FSH and LH are two types of hormones that stimulate gonads.
• They are known as gonadotropins.
• These two hormones are essential for reproduction.
• The cells of the anterior pituitary secrete gonadotrophins.
• Both hormones are large glycoproteins made up of alpha and beta subunits.
• The alpha subunit of both FSH and LH are identical while the beta subunit endows the ability to bind to a specific receptor, discriminating between the two enzymes.
• Levels of FSH and LH reach their highest value during ovulation.
• The release of both FSH and LH is stimulated by GnRH released by the hypothalamus.
• Negative feedback mechanisms regulate the release of these hormones.

Difference Between FSH and LH

Definition

FSH is a peptide produced by the anterior lobe of the pituitary gland, which regulates the development of the ovarian follicle in females and stimulates the production of spermatozoa in males while LH refers to a hormone produced by the anterior lobe of the pituitary gland, which stimulates maturation of the ovarian follicle and formation of the corpus luteum in females.

Other Names

In pharmaceutical preparations, FSH is also called follitropin while LH is called lutropin or interstitial cell–stimulating hormone (ICSH) in males.

Development of Primary Sex Organs

FSH is involved in the development of primary sex hormones while LH has no function in the development of primary sex organs.

In Females

While FSH stimulates the growth of ovarian follicle, LH stimulates ovulation.

In Males

Spermatogenesis through the production of ABP by Sertoli cells is stimulated by FSH while the production of testosterone by Leydig cells is stimulated by LH.

Effect on Menstrual Cycle

Although FSH affects the first half of the menstrual cycle, LH has an effect on both first and the second half of the menstrual cycle.

Conclusion

FSH is one of the two types of gonadotrophins secreted by the anterior pituitary gland, stimulating the development of gonads as well as the ovarian follicle in females and spermatozoa in males. However, LH is the other type of gonadotrophin that stimulates ovulation in females and the production of testosterone in males. The main difference between FSH and LH is the role of each type of gonadotropin.

Reference:

1. “Follicle Stimulating Hormone.” You and Your Hormones, Available Here
2. “Luteinising Hormone.” You and Your Hormones, Available Here

Image Courtesy:

1. “cicle menstrual” By loudista (CC BY-SA 2.0) via flickr
2. “Figure 28 03 01” By OpenStax College – Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia