During early development, the egg cell undergoes repeated mitotic divisions in rapid succession. These lead to the addition in the number of cells in the zygote without adding to its size. i.e. there is no growth in cell.
The Cleavage can be defined as "the progressive subdivisions of the zygote by mitotic cell divisions into increasing number of cells of progressively decreasing size"
Pattern of cleavage
- Right cleavage
- Bilateral cleavage
- Spiral cleavage