Motor proteins move chromosomes along the kinetochore microtubules as they become shorten by depolymerizing at their kinetochore ends. Motor proteins at the spindle poles move in the chromosomes with the microtubules depolymerizing at the poles. As the animal increase in length, the spindle poles extend away from each other. This pulling away is due to overlapping nonkinetochore microtubules moving away from each other using motor proteins.,
