In frogs, testes are attached to kidneys by a double fold of peritoneum known as :

Options

A. Pericardium
B. Mesorchium
C. Urinogenital duct
D. Vasa efferentia

Answer

To solve the question regarding the attachment of testes to kidneys in frogs, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the name of the double fold of peritoneum that attaches the testes to the kidneys in frogs.

2. **Defining Peritoneum**: Peritoneum is a serous membrane that lines the abdominal cavity and covers the abdominal organs. It plays a crucial role in supporting the organs and allowing movement.

3. **Identifying the Structure in Frogs**: In male frogs, there are two pairs of testes, which are located near the kidneys. The testes are attached to the upper part of the kidneys.

4. **Recognizing the Type of Attachment**: The attachment of the testes to the kidneys is facilitated by a double fold of the peritoneum.

5. **Naming the Double Fold**: This specific double fold of peritoneum that connects the testes to the kidneys is known as the **mesorchium**.

6. **Evaluating the Options**:
- Option 1: Pericardium - Incorrect (it is related to the heart).
- Option 2: Mesorchium - Correct (this is the name we identified).
- Option 3: Urinogenital duct - Incorrect (this is a different structure).
- Option 4: Vas deferens - Incorrect (this is also a different structure).

7. **Conclusion**: The correct answer is that in frogs, the testes are attached to the kidneys by a double fold of peritoneum known as **mesorchium**.

### Final Answer:
In frogs, testes are attached to kidneys by a double fold of peritoneum known as **mesorchium**.