Question

Why does only one egg rather than four eggs develop during oogenesis?

Answer 1

Oogenesis:

1. The process of the ovum differentiating into a cell capable of continuing to develop when fertilized is known as oogenesis.
2. It grows through maturation from the original oocyte.
3. The embryonic stage is when oogenesis begins.
4. During oogenesis, there is a meiotic division that is unequal.
5. After 1st meiotic division, primary oocytes divide unequally resulting in the larger secondary oocyte and a tiny first polar body.
6. The secondary oocyte retains the major bulk of the cytoplasm of the primary oocyte.
7. Similarly, the second meiotic division is also unequally distributed and leads to the formation of a larger ovum or ootid and the second polar body.
8. The unequal cytoplasmic division ensures that the egg has ample nutrients.
9. Thus, due to unequal division, only one egg develops during oogenesis compared to four sperms after meiotic division in oocytes and spermatocytes, respectively.