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Prometaphase is the phase of mitosis following prophase and preceding metaphase, in eukaryotic somatic cells. Prometaphase is sometimes simply included as part of the end of prophase and early metaphase. In prometaphase, the nuclear membrane breaks apart into numerous "membrane vesicles", and the chromosomes inside form protein structures called kinetochores.〔(【引用サイトリンク】url=http://www.nature.com/scitable/definition/prometaphase-281 )〕 Kinetochore microtubules emerging from the centrosomes at the poles (ends) of the spindle reach the chromosomes and attach to the kinetochores,〔 throwing the chromosomes into agitated motion. Other spindle microtubules make contact with microtubules coming from the opposite pole. Forces exerted by protein "motors" associated with spindle microtubules move the chromosomes toward the center of the cell. ==Types of microtubules== The microtubules are composed of two types, ''kinetochore microtubules'' and ''non-kinetochore microtubules''. * Kinetochore microtubules begin searching for kinetochores to attach to. * A number of ''non-kinetochore microtubules'' or ''polar microtubules'' find and interact with corresponding nonkinetochore microtubules from the opposite centrosome to form the mitotic spindle. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「prometaphase」の詳細全文を読む スポンサード リンク
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