![]() Given length constraints the focus will be primarily on vertebrate tissue culture cells.Įlectron microscopy (EM) has provided detailed information about the organization of spindle microtubules throughout mitosis ( Mastronarde et al., 1993 McDonald et al., 1992 McIntosh and Landis, 1971). In the following sections, the architecture, formation and dynamics of the midzone and the contribution of the midzone to chromosome segregation and cytokinesis will be discussed and illustrated on the poster. Note that the midbody forms after the midzone and is a distinct structure that contains complexes required for abscission ( Fededa and Gerlich, 2012). In telophase, midzone microtubules are compacted into a structure called the midbody or intracellular bridge ( Hu et al., 2012), which is the location of abscission, the final step in generating two independent daughter cells ( Lee et al., 2012). The midzone plays an important role in specifying the location of contractile ring assembly, resulting in the formation of two separate daughter cells ( Green et al., 2012). Here, I refer to the structure that forms between the segregating chromosomes as the midzone, and the microtubules within it the midzone microtubules. The microtubules that comprise the structure have been called interchromosomal, interpolar, interzonal or midzone microtubules ( Green et al., 2012 Glotzer, 2009 Mastronarde et al., 1993). This microtubule-rich region has been referred to by many different names, including the central spindle, midzone and anaphase spindle. As the chromosomes are segregated in anaphase, the microtubules between the segregating chromosomes become more prominent. The metaphase spindle is composed of kinetochore microtubules, which link the chromosomes to the spindle, astral microtubules, which radiate from each spindle pole toward the cell periphery, and overlapping microtubules, which extend from each half spindle toward the spindle midplane, connecting the two halves of the bipolar spindle ( McIntosh et al., 2012). The spindle generates forces to align the chromosomes at the metaphase plate and segregate them during anaphase. The mitotic spindle is a bipolar, microtubule-based structure that is responsible for chromosome segregation during cell division.
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