Which of the following statements is incorrect?

Options

A. Placenta allows exchange of materials between mother and fetus.
B. The fetal part of the placenta consists of the cells of the chorion which produce projections called chorionic villi.
C. Antibody cannot cross the placenta from mother to fetus.
D. Placenta secretes pregnancy hormones required for supporting fetal growth and metabolic changes in mother during pregnancy.

Answer

To determine which statement is incorrect regarding the placenta and its functions, we can analyze each option provided.

1. **Statement 1**: "Placenta allows exchange of materials between mother and fetus."
- This statement is **true**. The placenta facilitates the transfer of nutrients, gases, and waste products between the mother and the fetus.

2. **Statement 2**: "The fetal part of the placenta consists of the cell of chorion, which provides projections called chorionic villi."
- This statement is also **true**. The chorion is the outermost fetal membrane, and the chorionic villi are projections that increase the surface area for exchange between maternal and fetal blood.

3. **Statement 3**: "The blood here is transmitted or transfused between the fetus and the mother."
- This statement is **true** in the context that while the blood does not mix, the placenta allows for the exchange of substances between maternal and fetal blood.

4. **Statement 4**: "The antibody cannot cross the placenta from mother to fetus."
- This statement is **incorrect**. In fact, certain antibodies, particularly IgG, can cross the placenta and provide passive immunity to the fetus.

5. **Statement 5**: "Placenta secretes pregnancy hormone required for supporting fetal growth, metabolic changes in mother during pregnancy."
- This statement is **true**. The placenta produces hormones such as hCG (human chorionic gonadotropin) that are crucial for maintaining pregnancy.

Based on the analysis, the incorrect statement is **Statement 4**.