Anaphase

After spindle is formed and chromosomes have arranged on equatorial plate, chromosomes split at centromeres also. Sister centromeres separate from each other, so that the two sister chromatids are separate structures and can now be called chromosomes. These sister chromatids or daughter chromosomes now move towards opposite poles of spindle (Fig. 7.3f). The mechanism of movement of chromosomes at anaphase has been explained in different ways by different workers. It seems that there is repulsion between centrosomes and that there is contraction of spindle fibres which helps the movement (consult next main topic for details).