Zytokinese

Zytokinese, or cytokinesis in English, is the process by which the cytoplasm divides after chromosome segregation during cell division, producing two distinct daughter cells. The timing typically overlaps with late mitosis or meiosis and completes cell division after the nuclei have divided.

In animal cells, cytokinesis occurs via constriction of a contractile actomyosin ring at the cell cortex. This ring forms a cleavage furrow that pinches inward, progressively separating the cytoplasm until two cells remain. The process is driven by actin filaments and myosin II motors and is coordinated by signaling pathways, including Rho family GTPases that organize the cytoskeleton. Microtubules help position and regulate the site of division.

In plant cells, rigid cell walls prevent cleavage furrow formation. Instead, vesicles derived from the Golgi apparatus accumulate at the center of the cell to form a cell plate. The plate is assembled within a phragmoplast, a microtubule-based structure, and fuses with the parental plasma membrane to create two separate daughter cells, with new cell walls developing between them.

Cytokinesis ensures proper distribution of cytoplasmic contents and organelles and completes cell division. Errors can lead to multinucleated cells or unequal partitioning of cytoplasm, which may affect cell function and viability. While mechanisms differ, the overarching goal is the same: physically split the cytoplasm to yield two genetically identical daughter cells.