PROMETAPHASE
Prometaphase is the second stage of the five stages of the mitotic process of cell division. It begins with quick disintegration of the nuclear membrane into small fragments, which are undistinguishable from fragments of the endoplasmic reticulum. In chromosomes, in the each centromeric side, special structures, which are called kinetochores, are formed during prometaphase. They are attached to a certain group of microtubules, which are called kinetochore fibers, or, kinetochore microtubules. These fibers stretch from both sides of every chromosome to oppo site directions and interact with the fibers of the bipolar spindle. As this takes place, chromosomes begin to move intensively.