Trophoblast is not involved in the formation of

Options

A. Protective and trophic membranes
B. Foetal portion of placenta
C. Body of developing embryo
D. Chorionic villi

Answer

### Step-by-Step Solution:

1. **Understanding Trophoblast**: The trophoblast is the outer layer of cells of the blastocyst, which is a structure formed during the early development of mammals.

2. **Structure of Blastocyst**: The blastocyst consists of two main parts: the inner cell mass and the trophoblast. The inner cell mass will eventually develop into the embryo, while the trophoblast surrounds this inner cell mass.

3. **Functions of Trophoblast**: The trophoblast has several important functions:
- It provides protection to the developing embryo as it is the outer layer.
- It is involved in the formation of the fetal portion of the placenta.
- It forms the chorionic villi, which are finger-like projections in the placenta that help in the exchange of nutrients and gases between the mother and the fetus.

4. **Identifying What Trophoblast Does Not Form**: Since the inner cell mass is responsible for forming the body of the developing embryo, the trophoblast does not contribute to this formation.

5. **Conclusion**: Therefore, the correct answer to the question "Trophoblast is not involved in the formation of" is the body of the developing embryo.

### Final Answer:
The body of the developing embryo.

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