cytokinezis

Cytokinesis is the final stage of cell division, following mitosis or meiosis. It is the process by which the cytoplasm of a single eukaryotic cell divides into two daughter cells. While mitosis or meiosis segregates the genetic material into two distinct nuclei, cytokinesis ensures that each new nucleus is enclosed within its own cell membrane and cytoplasm.

The mechanism of cytokinesis differs between animal and plant cells. In animal cells, a contractile ring composed of actin and myosin filaments forms around the equator of the cell. This ring constricts, pinching the cell membrane inward and creating a cleavage furrow. Eventually, the furrow deepens until the cell is completely divided into two.

In plant cells, the presence of a rigid cell wall prevents the formation of a cleavage furrow. Instead, a cell plate forms in the middle of the cell. Vesicles derived from the Golgi apparatus gather at the metaphase plate and fuse, forming a flattened sac. This sac expands outward, depositing new cell wall material between the two developing daughter cells until it completely separates them.

Cytokinesis is a crucial process for growth, development, and reproduction in all eukaryotic organisms. Errors in cytokinesis can lead to aneuploidy, where daughter cells have an abnormal number of chromosomes, which can contribute to various diseases, including cancer.