Metaphase is the stage of mitosis following prophase. In metaphase all of the chromosomes have lined up in the center of the cell along an imaginary line called the metaphase plate. The sister chromatids are attached to each other by the centromere. Also during metaphase the centrioles have completed their migration to the poles of the cells and have developed spindle fibers. The spindle fibers made by centrioles attach to the chromosomes in preparation to pull one copy of each sister chromatid to each pole of the cell which will happen in the next stage of mitosis. During metaphase there is no nuclear envelope surrounding the chromosomes so they are in the cytoplasm at this time.
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