Answer: mitosis and meiosis. During mitosis, the spindle fibers are called the mitotic spindle.
Explanation: Spindle fibers form a protein structure that divides the genetic material in a cell. The spindle is necessary to equally divide the chromosomes in a parental cell into two daughter cells during both types of nuclear division: mitosis and meiosis. During mitosis, the spindle fibers are called the mitotic spindle.
