In the mitotic cell cycle, during the synthesis stage of interphase the DNA is replicated in each chromosome histone protein. In the first stage of mitosis, prophase, the chromosomes become visible due to shortening and condensing, each chromosome is made up of two sister chromatids joined at the centromere that may not be visible until late prophase. During metaphase, the chromosomes line up on the equator of the spindle. In anaphase, the sister chromatids are separated by the division of the centromere and are drawn to opposite poles by the shortening of the microtubules that form the spindle. In telophase the daughter chromosomes have reached either pole, the chromosomes uncoil becoming less visible and nuclear membrane reforms thus forming two daughter nuclei.