很多肝細胞是多倍體，含有4倍,、8倍,、16倍或更多倍的單倍體染色體組，盡管這一現(xiàn)象的重要性并不清楚?，F(xiàn)在,，用小鼠所進行的一項研究表明，肝細胞在活體中既可增加也可降低它們的多倍性,。多倍性逆轉以前被認為是減數分裂所獨有的,，但這項工作表明，它也可出現(xiàn)在正常體細胞中,。
多倍性的增加是通過失敗的胞質分裂出現(xiàn)的,，而多倍性的減少則是多極性有絲分裂的一個結果。所導致的遺傳異質性在肝受傷之后也許是有利的,，在這個時候,，具有遺傳穩(wěn)定性的細胞將會從事先存在的一組多樣化基因型中被選擇出來。（生物谷Bioon.com）
生物谷推薦英文摘要：
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.
