The second maturation division of the mammalian ovum occurs :-

Options

A. In the Graafian follicle following the first maturation division
B. Shortly after ovulation before the ovum makes entry into the Fallopian tube
C. Until after the ovum has been penetrated by a sperm
D. Until the nucleus of the sperm has fused with that of the ovum

Answer

To solve the question regarding when the second maturation division of the mammalian ovum occurs, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Maturation Divisions**: The maturation divisions of the ovum refer to the meiotic divisions that occur during oogenesis. The first maturation division occurs before ovulation, resulting in a secondary oocyte and a polar body.

2. **Identifying the Timing of the Second Maturation Division**: The second maturation division, which is also a meiotic division, does not occur until the ovum is fertilized. This means that the ovum remains in a suspended state until a sperm cell penetrates it.

3. **Evaluating the Options**:
- **Option 1**: "In the Graafian follicle following the first maturation division" - This is incorrect because the second maturation division does not occur in the follicle; it occurs after fertilization.
- **Option 2**: "Shortly after ovulation" - This is also incorrect. The ovum is released during ovulation but does not complete the second maturation division until fertilization occurs.
- **Option 3**: "Until after the ovum has been penetrated by a sperm" - This is the correct answer. The second maturation division occurs only after the sperm has penetrated the ovum.

4. **Conclusion**: The correct answer is that the second maturation division of the mammalian ovum occurs until after the ovum has been penetrated by a sperm.

### Final Answer:
The second maturation division of the mammalian ovum occurs until after the ovum has been penetrated by a sperm.

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