Immediately after ovulation, the mammalian egg is covered by a membrane known as

Options

A. Chorion and allantois
B. Zona pellucida
C. Corona radiata
D. Vitelline membrane.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the membrane that covers the mammalian egg immediately after ovulation.

2. **Analyzing the Options**:
- **Option A: Chorion and Allantois**: The chorion forms part of the placenta, and the allantois is an extra-embryonic sac. Neither of these options directly relates to the immediate covering of the egg after ovulation.

- **Option B: Zona Pellucida**: This is a thick, transparent membrane that surrounds the mammalian ovum before implantation. This option seems relevant as it is known to cover the egg.

- **Option C: Corona Radiata**: This refers to the layer of small follicular cells that surround the ovum in the Graafian follicle and accompany the ovum upon its release. While it is associated with the ovum, it does not serve as the primary covering after ovulation.

- **Option D: Vitelline Membrane**: This is a membrane that surrounds and is secreted by the fertilized ovum. However, it is not the immediate covering after ovulation.

3. **Identifying the Correct Answer**: After evaluating all the options, the correct answer is **Option B: Zona Pellucida**, as it is the membrane that surrounds the mammalian egg immediately after ovulation.

4. **Conclusion**: Therefore, the mammalian egg is covered by the zona pellucida immediately after ovulation.

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