Step 1: Understanding the Concept:
The onset of male puberty is regulated by a cascade of signals along the Hypothalamic-Pituitary-Gonadal (HPG) axis. The hypothalamus acts as the primary master control center, releasing neurohormones that signal the anterior pituitary gland to manufacture and release secondary chemical messengers called gonadotropins.
Step 2: Detailed Explanation:
Let's break down the hormonal sequence step-by-step:
1. At puberty, the hypothalamus increases its pulsatile release of Gonadotropin-Releasing Hormone (GnRH).
2. GnRH travels to the anterior pituitary gland and binds to specific receptors.
3. This stimulation causes the anterior pituitary to secrete two essential gonadotropins directly into the bloodstream:
- Luteinizing Hormone (LH): Acts on the Leydig cells in the testes to stimulate the synthesis and secretion of male hormones (androgens/testosterone).
- Follicle-Stimulating Hormone (FSH): Acts on the Sertoli cells in the testes to support spermatogenesis and stimulate the release of factors essential for sperm maturation.
Androgens and testosterone are downstream steroid hormones produced by the testes as a result of this signaling, rather than being gonadotropins themselves. Therefore, LH and FSH are the two true gonadotropins stimulated by GnRH.
Step 3: Final Answer:
The two gonadotropins are Luteinising Hormone and Follicle Stimulating Hormone, matching option (C).