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, let's analyze each option provided:

1. **Statement 1**: "Placenta allows exchange of materials between mother and fetus."
- **Analysis**: This statement is correct. The placenta serves as a vital connection between the mother and the fetus, facilitating the exchange of nutrients, gases (like oxygen and carbon dioxide), and waste products.

2. **Statement 2**: "The fetal part of the placenta consists of the cells."
- **Analysis**: This statement is also correct. The fetal part of the placenta is made up of chorionic cells, which form structures called chorionic villi that increase the surface area for material exchange.

3. **Statement 3**: "Antibody cannot cross the placenta from mother to fetus."
- **Analysis**: This statement is incorrect. In fact, certain antibodies, specifically IgG antibodies, can cross the placenta from the mother to the fetus, providing the fetus with passive immunity.

4. **Statement 4**: "Placenta secretes pregnancy hormones required for supporting fetal growth and metabolic changes in mother during pregnancy."
- **Analysis**: This statement is correct. The placenta produces various hormones, such as human placental lactogen (HPL), which are essential for maintaining pregnancy and supporting fetal development.

**Conclusion**: The incorrect statement is **Statement 3**: "Antibody cannot cross the placenta from mother to fetus."