Final answer:
During male sexual maturation, the deepened voice and increased muscle mass are due to the hormone testosterone, which is released when the hypothalamus secretes GnRH, stimulating the anterior pituitary gland to release LH and FSH. LH causes the testes to secrete testosterone, leading to secondary sexual characteristics.
Step-by-step explanation:
Understanding Male Sexual Maturation
The development of a deepened voice and increased muscle mass during male sexual maturation are processes primarily driven by the hormone testosterone. The release and production of testosterone are regulated by a hormonal chain reaction that begins in the brain. The hypothalamus releases Gonadotropin-releasing hormone (GnRH), which signals the anterior pituitary gland to secrete Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH). LH directly causes the Leydig cells in the testes to secrete testosterone. This surge in testosterone is responsible for secondary sexual characteristics, including the maturation of sperm (spermatogenesis), deepening of the voice, and increase in muscle bulk. On the other hand, FSH stimulates the Sertoli cells to support spermatogenesis, but it does not impact voice or muscle development directly.
As a result, the processes that explain the development of deepened voice and increased muscle mass during male sexual maturation are:
- Gonadotropin-releasing hormone (GnRH) stimulates the release of testosterone.
- Luteinizing hormone (LH) causes the testes to secrete testosterone.
The release of testosterone does not involve the targeting of adrenal glands by the hormone, nor is there a role for estrogen production by Sertoli cells in these particular changes.