Order of development of secondary sexual characteristic in male –
**Core Concept**
The development of secondary sexual characteristics in males is a complex process influenced by the hypothalamic-pituitary-gonadal (HPG) axis. This process is driven by the secretion of gonadotropin-releasing hormone (GnRH), which stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland. These hormones, in turn, regulate the production of testosterone by the Leydig cells in the testes, leading to the development of secondary sexual characteristics.
**Why the Correct Answer is Right**
The correct order of development of secondary sexual characteristics in males is:
- **Growth of facial hair**, followed by
- **voice deepening**, then
- **enlargement of the testes**,
- **proliferation of sebaceous glands** (leading to acne),
- **development of axillary and pubic hair**, and finally
- **enlargement of the penis**. This sequence is regulated by the increasing levels of testosterone, which stimulates the growth and development of these secondary sexual characteristics.
**Why Each Wrong Option is Incorrect**
- **Option A:** This option is not specific and does not follow the correct sequence of development.
- **Option B:** This option is incorrect as the development of axillary and pubic hair precedes the development of facial hair.
- **Option C:** This option is incorrect as the enlargement of the penis is the final step in the development of secondary sexual characteristics.
- **Option D:** This option is incorrect as the sequence of development is not accurately represented.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the development of secondary sexual characteristics in males is a gradual process influenced by the levels of testosterone, which are regulated by the HPG axis. Any disruptions to this axis, such as hypogonadism or hypergonadism, can lead to abnormalities in the development of these characteristics.
**Correct Answer: D. voice deepening, enlargement of the testes, proliferation of sebaceous glands, development of axillary and pubic hair, enlargement of the penis, growth of facial hair**