Question

When does extrusion of the second polar body occur?

Answer 1

Extrusion of the second polar body:

1. Extrusion of the second polar body of an egg nucleus generally occurs much before the fusion of the chromosomes seems to happen (that occurs during the first mitotic division of the zygote).
2. During oocyte–sperm fusion, second polar body expulsions occur and the cytoplasmic contents of the sperm cell membrane (now fused with the oocyte membrane) pass into the oocyte cytoplasm.
3. During fertilisation, the acrosome's secretion helps the sperm to enter into the cytoplasm of the ovum.
4. This induces completion of the 2nd meiotic division of secondary oocytes.
5. The second meiotic division also results in the formation of a second polar body and a haploid ovum.
6. Then the haploid nucleus of the sperms and that of the ovum fuses together to form a diploid zygote.