On the basis of nature of maternal and foetal tissues, the types of placentae are
I. Hemochorial placenta
II. Hemoendothelial placenta
III. Cotyledonary placenta
IV. Deciduate placenta
Choose the correct answers

Options

A. I, II, III are correct
B. I and II are correct
C. II and IV are correct
D. I, II and IV are correct

Answer

To solve the question regarding the types of placenta based on the nature of maternal and fetal tissues, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for the types of placenta classified based on the nature of maternal and fetal tissues. We need to identify which of the given options fit this classification.

2. **Identify the Types of Placenta**:
- **Hemochorial Placenta**: In this type, the chorionic epithelium is in direct contact with maternal blood. This is seen in humans and some primates.
- **Hemoendothelial Placenta**: Here, fetal capillaries come in direct contact with maternal blood, meaning the chorionic epithelium and mesoderm are absent. This type is observed in some rodents.
- **Cotyledonary Placenta**: This type is based on the gross shape of the placenta and is not classified based on maternal and fetal tissue types. It involves specific attachment sites (cotyledons) and is seen in ruminants.
- **Deciduate Placenta**: This type is classified based on the degree of association between maternal and fetal tissues, particularly how much maternal tissue is shed at birth. It is not based solely on the nature of the tissues.

3. **Analyze Each Option**:
- **Option I (Hemochorial)**: Correct, as it is based on maternal and fetal tissues.
- **Option II (Hemoendothelial)**: Correct, as it is also based on maternal and fetal tissues.
- **Option III (Cotyledonary)**: Incorrect, as it is based on the shape of the placenta, not the tissue types.
- **Option IV (Deciduate)**: Incorrect, as it is based on the association degree, not the tissue types.

4. **Conclusion**: The correct types of placenta based on the nature of maternal and fetal tissues are Hemochorial and Hemoendothelial. Therefore, the correct answer is **Option B (1 and 2)**.