In early prophase of mitosis and later prophase of meiosis, the chromosomes split lengthwise into two identical chromatids held together by the CENTROMERE. 在有丝分裂前期的开始以及减数分裂前期的结尾，染色体通过着丝点形成两个完全相同的染色单体。
At the beginning of prophase the chromosomes each consist of two highly condensed chromatids attached to each other at a centromere. 分裂前期，高度浓缩的两个染色单体通过着丝粒连接在一起。
