www.jcb.org/cgi/doi/10.1083/jcb.201210007 JCB 131 JCB: Review

Mitotic and meiotic spindles are precisely positioned within eukaryotic cells for several reasons. In animal cells, spindle posi-tion determines the location of contractile ring assembly (Green et al., 2012). Thus, placing a spindle in the center of the cell will result in daughter cells of equal size, whereas positioning the spindle asymmetrically results in daughter cells of different sizes. In oocytes, the extreme asymmetrical positioning of the meiotic spindle allows expulsion of three fourths of the chromo-somes into two tiny polar bodies while preserving most of the cytoplasm in the egg for the developing zygote. In polarized cells, where proteins and RNAs are asymmetrically distributed before division, the orientation of the spindle relative to the polarity axis determines whether the daughter cells will have the same or different developmental fates. An excellent review of the developmental context of spindle positioning is provided b