Cytokinesis is the physical process of cell division that divides the cytoplasm of a parental cell into two daughter cells. It occurs concurrently with two types of nuclear division called mitosis and meiosis, which occur in animal cells. Cytokinesis performs an essential process to separate the cell in half and ensure that one nucleus ends up in each daughter cell. Cytokinesis starts during the nuclear division phase called anaphase and continues through telophase. The process of cytokinesis can be divided into four stages: initiation, contraction, membrane insertion, and completion. During cytokinesis, a ring of protein filaments called the contractile ring forms around the equator of the cell just beneath the plasma membrane. The contractile ring shrinks at the equator of the cell, pinching the plasma membrane inward and forming what is called a cleavage furrow. Eventually, the contractile ring shrinks to the point that there are two separate cells each bound by its plasma membrane. In animal cells, cytokinesis is achieved through the constriction of the cell by a ring of contractile microfilaments consisting of actin and myosin. In plant cells, the cytoplasm is divided by the formation of a new cell wall, called the cell plate, between the two daughter cells. Once the daughter cells are separated, cellulose synthesis begins, and the cell plate becomes a primary cell wall.