PROPHASE
Prophase is the first stage of the five stages of the mitotic process of cell division. Usually it is the most long-lasting. Chromatids become shorter (up to 4 per cent of their original length) and thicken as the result of helix formation and condensation. Centrioles diverge to the opposite cellular poles. Short microtubules stretch from each centriole like rays. Nucleoli grow smaller, because their DNA partially transfers into chromatids. By the end of prophase, nuclear membrane disintegrates and forms mitotic spindle.