Cells with multiple centrosomes rarely undergo multipolar cell divisions, and when they do occur, the progeny of these divisions are typically inviable. This low frequency of viable multipolar divisions means multipolar divisions cannot account for the observed rates of chromosomal instability in CIN cells. [@ganem_mechanism_2009]

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While multipolar cell division can theoretically result from the presence of extra centrosomes in cells, these divisions are uncommon because cells with supernumerary centrosomes typically cluster their centrosomes to undergo bipolar rather than multipolar divisions. The rarity of multipolar divisions appears to be driven by selection against the aneuploid progeny they generate, as chromosome missegregation alone is insufficient for aneuploid cell propagation and compromises the proliferation capacity of diploid cells. Instead, extra centrosomes promote chromosome missegregation primarily during bipolar division through mechanisms such as transient multipolar spindle intermediates that allow merotelic attachments to accumulate, thereby generating chromosomal instability without the need for completing multipolar division. What remains less clear is whether the inviability of multipolar division progeny reflects an absolute inability to tolerate the extreme aneuploidy resulting from tripartite or higher-order chromosome segregation, or whether rare progeny could survive with additional phenotypic changes that permit propagation of highly aneuploid karyotypes.

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