Which extra-embryonic membrane in human prvents desiccation of the embryo inside the uterus?

Options

A. Amnion
B. Chorion
C. Allantois
D. Yolk sac

Answer

### Step-by-Step Solution:

1. **Identify the Extra-Embryonic Membranes**: In humans, there are three main extra-embryonic membranes: the amnion, chorion, and allantois.

2. **Understand the Functions of Each Membrane**:
- **Chorion**: Formed from the outer ectoderm, it plays a role in the formation of the placenta and acts as a shock absorber.
- **Amnion**: Formed from the outer layer of the somatic mesoderm, it surrounds the fetus and provides a protective fluid-filled cavity.
- **Allantois**: Also formed from the outer layer of the mesoderm, it is involved in the formation of the placenta and assists in respiration and nutrition.

3. **Focus on the Amnion**: The amnion is particularly important as it surrounds the fetus and contains amniotic fluid, which serves to cushion the fetus and prevent desiccation (drying out).

4. **Conclude the Answer**: Based on the functions discussed, the extra-embryonic membrane that prevents desiccation of the embryo inside the uterus is the **amnion**.

### Final Answer:
The extra-embryonic membrane in humans that prevents desiccation of the embryo inside the uterus is the **amnion**.

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