Why do all copulations not lead to fertilisation and pregnancy ? The root cause is ______

Options

A. Due to numerous sperms and one ovum
B. Due to less progesterone
C. Ovum and sperms are not transperted simultaneously to the ampullary - isthmic junction
D. Due to non- formation of corpus luteum

Answer

**Step-by-Step Solution:**

1. **Understanding Copulation**: Copulation is the act of sexual intercourse where sperm is deposited in the female reproductive tract.

2. **Pathway of Sperm**: After copulation, sperm travels through the female genital tract, entering the cervix, moving through the uterus, and then into the fallopian tubes.

3. **Pathway of Ovum**: The ovum, released from the ovary, is captured by the fimbriae of the fallopian tube and travels towards the ampulla-isthmus junction, which is the site of fertilization.

4. **Site of Fertilization**: Fertilization occurs at the ampulla-isthmus junction, where the sperm and ovum must meet.

5. **Requirement for Fertilization**: For fertilization to occur, both the sperm and ovum must arrive at the ampulla-isthmus junction simultaneously.

6. **Reasons for Lack of Fertilization**:
- If the sperm reaches the junction but the ovum has already passed it or hasn't reached it yet, fertilization will not occur.
- Conversely, if the ovum is at the junction but the sperm does not arrive, fertilization will also not take place.

7. **Conclusion**: Therefore, the root cause of why all copulations do not lead to fertilization and pregnancy is the lack of simultaneous arrival of both gametes at the site of fertilization.

**Final Answer**: The root cause is the lack of simultaneous arrival of sperm and ovum at the ampulla-isthmus junction.

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