Interphase is often included in discussions of mitosis, but interphase is technically not part of mitosis, but rather encompasses stages G1, S, and G2 of the cell cycle. Chromosomes are not clearly discerned in the nucleus, although a dark spot called the nucleolus may be visible. Prophase Chromatin in the nucleus begins to condense and becomes visible in the light microscope as chromosomes. The nucleolus disappears. Centrioles begin moving to opposite ends of the cell and fibers extend from the centromeres.
Some fibers cross the cell to form the mitotic spindle.
Prometaphase The nuclear membrane dissolves, marking the beginning of prometaphase. Proteins attach to the centromeres creating the kinetochores. Microtubules attach at the kinetochores and the chromosomes begin moving. Metaphase Spindle fibers align the chromosomes along the middle of the cell nucleus. This line is referred to as the metaphase plate.