Question

Write about cleavage.

Answer 1

Cleavage:

1. It is a sequence of synchronized mitotic cell divisions of the fertilized egg that leads to the formation of the blastomeres.
2. It changes the single-celled zygote into a multicellular embryo.
3. Once fertilization happens, the zygote starts cell division, during its passing through the oviduct.
4. This starting division is cleavage as it occurs in the zona pellucida where the growth of the cell does not occur.
5. Daughter cells are known as blastomeres which are nourished by nutrients that are produced by the uterine glands.
6. When the embryo comes to the 8-16 cell stage, it turns into a morula.
7. Mitotic division of cleavage continues until 4-8 days, during which the embryo turns into the blastocyst.
8. Here, the embryo has a fixed central cavity that is fluid-filled, also known as a blastocoel.