Cytokinesis (cell division proper) is a part of the mitotic terminal phase or telophase. In this period, a cleavage furrow emerges in the cell equator; it deepeans until the approaching membrane portions fuse. The cleavage furrow originates from an equatorial cytoplasmic constriction that is a bundle of circular microfilaments. Constriction of this ring compresses the cell cytoplasm, and two approximately equal parts are formed. The cleavage furrow at this time is still narrow, and two segregating cells are tightly adjacent to one another. The progress of telophase in the cell cytoplasm is factually a reverse repetition of the prophase steps. The daughter cells are often defined as postmitotic because it is not clear yet if they continue to divide or enter a steady state with specialized differentiation for a certain set of organelles.