Decidua which lakes part in the formation of maternal protion of the placent is

Options

A. Decidua basalis
B. Decidua capsularis
C. Decidua parietalis
D. Chorion

Answer

To answer the question regarding which decidua lacks a part in the formation of the maternal portion of the placenta, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Decidua**: The decidua is a modified form of the endometrium (the inner lining of the uterus) that plays a crucial role during pregnancy. It is involved in the formation of the placenta.

2. **Identify the Types of Decidua**: There are three main types of decidua:
- **Decidua Basalis**: This is the part of the decidua that is directly beneath the implanted embryo and contributes to the maternal portion of the placenta.
- **Decidua Capsularis**: This layer surrounds the embryo and is involved in the formation of the placenta but does not contribute to the maternal portion.
- **Decidua Parietalis**: This is the part of the decidua that lines the rest of the uterine cavity and does not contribute to the placenta.

3. **Identify the Non-Decidua Component**: The question also mentions "chorion," which is not a type of decidua. The chorion is the outermost fetal membrane that surrounds the embryo and contributes to the formation of the fetal portion of the placenta.

4. **Conclusion**: Based on the definitions and roles of each component, the decidua that does not participate in the formation of the maternal portion of the placenta is the **chorion**.

### Final Answer:
The decidua that lacks a part in the formation of the maternal portion of the placenta is **chorion**.

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