cleavage furrow

The cleavage furrow is a shallow, inward-denting groove that forms on a cell's surface during cell division, specifically in the process called cytokinesis. Its purpose is to help split one cell into two daughter cells. The furrow forms as a contractile ring made of protein fibers tightens around the middle of the cell, pulling the cell membrane inward. This tightening gradually deepens until the cell is pinched apart into two separate cells, each with its own nucleus and organelles. The cleavage furrow ensures that cell division is completed efficiently and correctly.