The mitotic spindle is a group of spindle fibers that divide chromosomes during mitosis. The spindle helps to split the chromosomes from a parental cell into two daughter cells.
According to Biology Online, the mitotic spindle develops outside the nucleus during mitosis. Nature Education reports that the mitotic spindle plays a role in chromosome division during metaphase and anaphase. During the beginning of mitosis, centrioles create poles at the opposite ends of the cell. During metaphase, chromosomes line up in the center of the cell, and the cell undergoes a checkpoint to ensure chromosomes are attached to the spindle prior to cell division. During anaphase, the spindle separates chromosomes to the opposite poles of the cell.