In metaphase, the chromosomes align in a formation called the metaphase plate in the center of the cell. The microtubules of the spindle apparatus have already attached to the kinetochores of the chromosomes. In animal cells, the spindle is associated with centrioles. When all of the chromosomes are aligned on the metaphase plate with microtubules connected to all of the kinetochores, the cell enters anaphase, the next stage of mitosis.