At which stage of the ovarian cycle are mammalian eggs most likely to become fertilized ?

Options

A. At the beginning of proliferative phase.
B. Immediately after ovulation.
C. During the middle of the secretory phase.
D. During the menstrual phase.

Answer

To determine at which stage of the ovarian cycle mammalian eggs are most likely to become fertilized, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Ovarian Cycle Phases**:
- The ovarian cycle consists of several phases: the menstrual phase, the follicular phase, ovulation, and the luteal (or secretory) phase.

2. **Identify the Phases**:
- **Menstrual Phase**: This is the bleeding phase where the uterine lining is shed.
- **Follicular Phase**: This phase involves the development of follicles in the ovaries.
- **Ovulation**: This is the release of a mature egg from the ovary, typically occurring around the 14th day of the cycle.
- **Luteal Phase (Secretory Phase)**: This phase occurs after ovulation and prepares the uterus for a potential pregnancy.

3. **Determine Timing of Fertilization**:
- Fertilization of the egg typically occurs shortly after ovulation when the egg is viable. The egg remains viable for fertilization for about 12 to 24 hours after it is released.

4. **Evaluate the Options**:
- **Option A**: At the beginning of the proliferative phase (not correct, as the egg is not yet matured).
- **Option B**: Immediately after ovulation (correct, as the egg is released and available for fertilization).
- **Option C**: During the middle of the secretory phase (not correct, as the egg has already been released and is no longer viable).
- **Option D**: During the menstrual phase (not correct, as no egg is available for fertilization).

5. **Conclusion**:
- The stage of the ovarian cycle when mammalian eggs are most likely to become fertilized is **immediately after ovulation**.

### Final Answer:
**Immediately after ovulation (Option B)**.

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