All extra embryonic membranes

Options

A. Take part in the formation of embryo
B. Does not take part in the embryo formation
C. Form the placenta
D. Perform the function of excretion of embryo

Explanation

### Step-by-Step Text Solution:

1. **Understanding Extra Embryonic Membranes**: Extra embryonic membranes are structures that develop alongside the embryo during its development. These membranes are crucial for various functions but do not contribute directly to the formation of the embryo itself.

2. **Identifying Functions of Extra Embryonic Membranes**: The primary functions of these membranes include:
- **Nourishment**: They provide nutrients to the developing embryo.
- **Gas Exchange**: They facilitate the exchange of gases (oxygen and carbon dioxide) between the mother and the embryo.
- **Waste Removal**: They help in the excretion of waste products from the embryo to the mother.

3. **Placenta Formation**: One of the key extra embryonic membranes is the placenta. The placenta is a specialized tissue that forms from the chorion (one of the extra embryonic membranes) and plays a vital role in connecting the embryo to the mother. It is responsible for nutrient uptake, waste elimination, and gas exchange.

4. **Conclusion on Embryo Formation**: While extra embryonic membranes are essential for supporting the embryo and facilitating its development, they do not become part of the embryo itself. Therefore, the statement "all extra embryonic membranes do not take part in the embryo formation" is accurate.

5. **Final Answer**: The correct option regarding extra embryonic membranes is that they do not take part in the formation of the embryo.