很多肝细胞是多倍体，含有4倍、8倍、16倍或更多倍的单倍体染色体组，尽管这一现象的重要性并不清楚。现在，用小鼠所进行的一项研究表明，肝细胞在活体中既可增加也可降低它们的多倍性。多倍性逆转以前被认为是减数分裂所独有的，但这项工作表明，它也可出现在正常体细胞中。
多倍性的增加是通过失败的胞质分裂出现的，而多倍性的减少则是多极性有丝分裂的一个结果。所导致的遗传异质性在肝受伤之后也许是有利的，在这个时候，具有遗传稳定性的细胞将会从事先存在的一组多样化基因型中被选择出来。（生物谷Bioon.com）
生物谷推荐英文摘要：
Nature doi:10.1038/nature09414
The ploidy conveyor of mature hepatocytes as a source of genetic variation
Andrew W. Duncan,Matthew H. Taylor,Raymond D. Hickey,Amy E. Hanlon Newell,Michelle L. Lenzi,Susan B. Olson,Milton J. Finegold& Markus Grompe
Mononucleated and binucleated polyploid hepatocytes (4n, 8n, 16n and higher) are found in all mammalian species, but the functional significance of this conserved phenomenon remains unknown1, 2, 3, 4. Polyploidization occurs through failed cytokinesis, begins at weaning in rodents and increases with age2, 5, 6, 7. Previously, we demonstrated that the opposite event, ploidy reversal, also occurs in polyploid hepatocytes generated by artificial cell fusion8, 9, 10. This raised the possibility that somatic ‘reductive mitoses’ can also happen in normal hepatocytes. Here we show that multipolar mitotic spindles form frequently in mouse polyploid hepatocytes and can result in one-step ploidy reversal to generate offspring with halved chromosome content. Proliferating hepatocytes produce a highly diverse population of daughter cells with multiple numerical chromosome imbalances as well as uniparental origins. Our findings support a dynamic model of hepatocyte polyploidization, ploidy reversal and aneuploidy, a phenomenon that we term the ‘ploidy conveyor’. We propose that this mechanism evolved to generate genetic diversity and permits adaptation of hepatocytes to xenobiotic or nutritional injury.
