Mitosis, cell division, occurs in phases. The process of nuclear division begins with the interphase. In the interphase the cell begins to prepare for the process by becoming involved in metabolic activity. Essentially, it is not an actual part of mitosis but rather the beginning of the intent of action taking place within the cell. Prophase is considered the beginning of mitosis because the centrioles begin to separate by moving to opposite sides within the cell. The extension of the fibers causes a mitotic spindle to form. During the next stage, the prometaphase, the nuclear membrane dissolves and chromosomes start moving to align with the mitotic spindle. Once they have moved into alignment, the phase is known as the metaphase. The chromosomes then separate into pairs on opposite sides of the cell during the anaphase. In the telophase, the cell begins to separate into two. The final stage that occurs with cells, cytokinesis, occurs when the two cells pinch apart and two daughter cells exist. Each of the cells has its own nucleus.