Anaphase is the third phase during mitosis (cell division). During anaphase, the chromosomes of the cell separate into sister chromatids. Spindle fibers form guide wires that attach to chromosomes at their centromere. Next, spindle fibers pull the chromatids to the poles of the cell. The purpose of moving the chromatids to the poles of the cell is to ensure that during cell division each resulting cell will receive all of the required genetic information.