During interphase, DNA is stretched out and read by the cell while chromosomes replicate but cannot be seen. In prophase, the nucleus disappears, sister chromatids pair up to form visible chromosomes, and centrioles duplicate and move to the poles. In metaphase, spindle fibers appear and line chromosomes up along the middle. In anaphase, spindle fibers pull the chromatids apart toward the centrioles. In telophase, spindle fibers and centrioles disappear as nuclei form around new chromosome sets and the cell splits into two identical cells through cytokinesis.