FIGURE 18-37 The stages of mitosis. (a) Upper panels show stages in cultured cells stained blue for DNA and green for tubulin. Lower diagrams show the different stages and the events that occur in each. Mitosis is a continuous process that has been divided into stages for ease of description. (b) Parts of a condensed chromosome in mitosis. The duplicated chromosome consists of two sister chromatids (each is a single DNA duplex), held together by cohesins at a constricted region called the centromere. The centromere is also the site where the kinetochore, which will make attachments to the kinetochore microtubules, forms.

[Part (a) micrographs courtesy of Torsten Wittmann.]