Here's a breakdown:
1. Mitosis: The nucleus divides (karyokinesis) and the chromosomes are distributed to the two daughter cells.
2. Cytokinesis: The cytoplasm divides. This is where the cleavage furrow appears.
Cleavage furrow formation:
* Contractile ring: A ring of microfilaments (mainly composed of actin) forms beneath the plasma membrane at the equator of the cell.
* Contraction: The microfilaments contract, pulling the cell membrane inwards and creating a groove known as the cleavage furrow.
* Division: The furrow deepens until it pinches off the cytoplasm, ultimately separating the two daughter cells.
So, the cleavage furrow appears in animal cells specifically after the nucleus has divided and during the process of dividing the cytoplasm.
