Meiotic division of male germ cells commence
## **Core Concept**
The question tests the understanding of the developmental biology of male germ cells, specifically the timing of meiotic division. **Spermatogenesis**, the process by which immature cells develop into mature sperm cells, involves both mitotic and meiotic divisions. Meiotic division is crucial for genetic diversity and reduction of chromosome number by half.
## **Why the Correct Answer is Right**
The correct answer, **C. At puberty**, indicates that meiotic division of male germ cells commences at puberty. This is accurate because spermatogenesis, including the meiotic phase, begins at puberty in males. The onset of puberty is marked by the increase in levels of gonadotropin-releasing hormone (GnRH) from the hypothalamus, leading to the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland. These hormones stimulate the testes to start producing sperm through spermatogenesis, which includes both mitotic and meiotic divisions.
## **Why Each Wrong Option is Incorrect**
- **Option A:** *Prenatally* - While it's true that the male germ cells undergo some development prenatally, meiotic division does not commence at this stage. In fact, male germ cells enter a quiescent phase and do not proceed with meiosis until puberty.
- **Option B:** *After 5 years of age* - This option is too vague and incorrect. The timing of meiotic division commencement is more specifically tied to puberty rather than a fixed age that might vary among individuals.
- **Option D:** *At 60 years of age* - This option is clearly incorrect. While some aspects of male reproductive capability may decline with age, the initiation of meiotic division in male germ cells does not begin at 60 years of age but rather at puberty.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **spermatogenesis is a continuous process** that starts at puberty and continues throughout a man's life, although the quality and quantity of sperm may decrease with age. This process takes approximately 70-80 days to complete.
## **Correct Answer:** C. At puberty.