Cytokinesis is the physical process of cell division, which 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 begins during the nuclear division phase called anaphase and continues through telophase. The first visible change of cytokinesis in an animal cell is the sudden appearance of a pucker, or cleavage furrow, on the cell surface. In animal cells and many unicellular eukaryotes, the structure that accomplishes cytokinesis is the contractile ring—a dynamic assembly composed of actin filaments, myosin II filaments, and many structural and regulatory proteins. 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.