In mammals, the testes occur in scrotal sacs outside the abdomen because of the

Options

A. presence of urinary bladder
B. presence of rectum
C. long vas-deferens
D. Requirement of low temperature for spermatogenesis

Answer

**Step-by-Step Solution:**

1. **Understanding the Location of Testes**: In mammals, the testes are located in the scrotal sacs, which are situated outside the abdominal cavity.

2. **Reason for External Location**: The primary reason for this external location is the requirement of a lower temperature for the process of spermatogenesis, which is the production of sperm.

3. **Temperature Requirement**: The optimal temperature for spermatogenesis is about 2 to 2.5 degrees Celsius lower than the normal internal body temperature. This lower temperature is crucial for the proper development and maturation of sperm.

4. **Role of the Scrotum**: The scrotum acts as a pouch that helps maintain this lower temperature necessary for sperm production.

5. **Development of Testes**: During fetal development, the testes initially form within the abdominal cavity but descend into the scrotal sacs around the seventh month of gestation. This descent is influenced by hormones, particularly testosterone.

6. **Conclusion**: Therefore, the testes are located in the scrotal sacs outside the abdomen to ensure that they remain at the optimal temperature required for effective spermatogenesis.

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