Question

Extrusion of second polar body from egg nucleus occurs-

• A. After entry of sperm and before completion of fertilisation.
• B. After completion of fertilisation
• C. Before the entry of sperm
• D. Without any relation with sperm entry

Answer 1

The correct option is A

After entry of sperm and before completion of fertilisation.

The correct option A:

Explanation of the correct option:

1. After the ovulation, the secondary oocyte remains arrested in meiosis-II cell division. During fertilization as the sperm enters the secondary oocyte “meiotic split” occurs.
2. The entry of sperm breaks the metaphase arrest of the oocyte and hence the meiosis-II cell division completes forming the zygote and the second polar body.
3. This entire process takes place only after the entry of sperm and before the completion of fertilization.

Final answer: Extrusion of the second polar body from the egg nucleus occurs after the entry of sperm and before completion of fertilization.