Villi of human placenta develop from

Options

A. Chorion and allantois
B. Allantois
C. Yolk sac
D. Both A and B

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the origin of the villi in the human placenta. Villi are small, finger-like projections that increase the surface area for nutrient and gas exchange between the mother and the fetus.

2. **Identifying the Options**: The options provided are:
- A. Chorion
- B. Allantois
- C. Yolk sac
- D. Both A and B

3. **Analyzing Each Option**:
- **Chorion**: The chorion is one of the membranes surrounding the embryo and plays a crucial role in the formation of the placenta. The villi of the placenta, known as chorionic villi, develop from the chorion.
- **Allantois**: The allantois is another embryonic membrane that is involved in waste disposal and gas exchange, but it does not directly form the villi of the placenta.
- **Yolk sac**: The yolk sac is primarily involved in early embryonic development and does not contribute to the formation of placental villi.

4. **Conclusion**: Since the villi of the human placenta develop from the chorion, the correct answer is option A, Chorion.

5. **Final Answer**: The villi of the human placenta develop from the Chorion (Option A).

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