Hormonal control of male reproductive system
The growth, maintenance, and functioning of male reproductive organs are under strict hormonal regulation. The key hormones involved in this control are Gonadotropin-releasing hormone (GnRH), Luteinizing hormone (LH), Follicle-stimulating hormone (FSH), Testosterone, and Inhibin.
1. Hypothalamus and Pituitary Regulation
The hypothalamus secretes Gonadotropin-releasing hormone (GnRH). GnRH stimulates the anterior pituitary gland to release: Luteinizing Hormone (LH) Follicle Stimulating Hormone (FSH)
2. Role of LH (Luteinizing Hormone)
LH is also called Interstitial Cell Stimulating Hormone (ICSH). It stimulates the Leydig cells (interstitial cells) present in the testis to produce testosterone. Testosterone is the principal androgen (male sex hormone) responsible for: Development of male secondary sexual characteristics (muscle mass, deep voice, facial hair, etc.). Maintaining the reproductive tract.
Promoting spermatogenesis in seminiferous tubules.
3. Role of FSH (Follicle Stimulating Hormone)
FSH acts on the Sertoli cells present in the seminiferous tubules. It stimulates spermatogenesis (the formation of sperm). Sertoli cells secrete: Androgen-binding protein (ABP): Helps in concentrating testosterone in the seminiferous tubules, essential for sperm production. Inhibin: A protein hormone that inhibits the release of FSH, providing negative feedback regulation to maintain hormonal balance.
4. Negative Feedback Mechanism
Testosterone inhibits GnRH and LH production when its levels are high. This prevents excessive testosterone production. Inhibin inhibits FSH secretion from the anterior pituitary, regulating sperm production.
Summary
Hypothalamus releases GnRH. Anterior Pituitary Gland responds by releasing LH and FSH.
LH stimulates Leydig Cells → Leydig Cells secrete Testosterone. Testosterone promotes:
Development of male secondary sexual characteristics. Maintenance of reproductive structures. Spermatogenesis in the seminiferous tubules. FSH stimulates Sertoli Cells, leading to: Androgen-binding protein (ABP) production (which keeps testosterone levels high in the testes). Inhibin production, which inhibits FSH secretion.