A special region of the centromeres of each pair of sister chromatids, the kinetochore, becomes attached to one or a bundle of spindle microtubules and hauling the chromatid toward the spindle pole.

• 每对姐妹染色单体着丝粒的特殊区域有一个动粒结构，与一根或一束纺锤体微管相连。细胞分裂后期，动粒结构起到马达的作用，使相连的微管发生去装配并将染色单体拉向纺锤体的两极。