The scrotum

Options

A. is a pouch of skin outside the abdominal cavity that encloses testes in all mammals.
B. contains detrusor muscle whose contraction moves the testes closer to the body during winter.
C. is covered externally by a serous membrane called tunica vaginalis.
D. maintains temperature of testes lower than core body temperature.

Answer

**Step-by-Step Solution:**

1. **Understanding the Scrotum:**
- The scrotum is a pouch-like structure made of skin that is located outside the pelvis region of males. Its primary function is to house and protect the testis.

2. **Identifying the Function of the Scrotum:**
- The scrotum plays a crucial role in regulating the temperature of the testis. It maintains the temperature of the testis at about 2 degrees Celsius lower than the core body temperature, which is essential for healthy sperm production.

3. **Analyzing the Statements:**
- The question provides several statements about the scrotum. We need to evaluate each statement to determine which one accurately describes the scrotum.

4. **Evaluating Each Statement:**
- **Statement 1:** "It is a pouch of skin outside the abdominal cavity that encloses testis in all mammals."
- This statement is incorrect because the scrotum is located outside the pelvis, not the abdominal cavity.

- **Statement 2:** "It contains detrusor muscles whose contraction moves the testis closer to the body during winter."
- This statement is incorrect. The detrusor muscle is involved in urination, not in moving the testis. The muscle responsible for this action is the dartos muscle.

- **Statement 3:** "It is covered externally by a serous membrane called tunica vaginalis."
- This statement is incorrect. The tunica vaginalis is indeed a membrane associated with the testis but is not an external covering of the scrotum itself.

- **Statement 4:** "It maintains body temperature of testis lower than the core body temperature."
- This statement is correct. The scrotum does maintain a lower temperature for the testis, which is crucial for sperm health.

5. **Conclusion:**
- The correct statement regarding the scrotum is that it maintains the body temperature of the testis lower than the core body temperature. Therefore, the answer to the question is option D.