Mitosis. Illustration of the stages of mitosis (nuclear division) and cytokinesis (cell division) from left to right. Periods between division are known as interphase (left). Early in mitosis, during prophase, chromosomes (red) condense. Each chromosome has replicated and is composed of two sister chromatids. The nuclear envelope (blue) disintegrates during prometaphase, and the chromosomes line up along the centre of the cell (metaphase, centre). Microtubules (black) attach to the chromosomes and pull the chromatids apart to opposite poles of the cell (anaphase). Two nuclei form and the cell begins to divide during telophase (second from right). This process is completed during cytokinesis to form two identical daughter cells (right).