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首页> 外文期刊>Human Reproduction Update >Meiosis in oocytes: predisposition to aneuploidy and its increased incidence with age
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Meiosis in oocytes: predisposition to aneuploidy and its increased incidence with age

机译：卵母细胞减数分裂：易致非整倍性及其随着年龄的增长而增加

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Mammalian oocytes begin meiosis in the fetal ovary, but only complete it when fertilized in the adult reproductive tract. This review examines the cell biology of this protracted process: from entry of primordial germ cells into meiosis to conception. The defining feature of meiosis is two consecutive cell divisions (meiosis I and II) and two cell cycle arrests: at the germinal vesicle (GV), dictyate stage of prophase I and at metaphase II. These arrests are spanned by three key events, the focus of this review: (i) passage from mitosis to GV arrest during fetal life, regulated by retinoic acid; (ii) passage through meiosis I and (iii) completion of meiosis II following fertilization, both meiotic divisions being regulated by cyclin-dependent kinase (CDK1) activity. Meiosis I in human oocytes is associated with an age-related high rate of chromosomal mis-segregation, such as trisomy 21 (Down’s syndrome), resulting in aneuploid conceptuses. Although aneuploidy is likely to be multifactorial, oocytes from older women may be predisposed to be becoming aneuploid as a consequence of an age-long decline in the cohesive ties holding chromosomes together. Such loss goes undetected by the oocyte during meiosis I either because its ability to respond and block division also deteriorates with age, or as a consequence of being inherently unable to respond to the types of segregation defects induced by cohesion loss.
机译：哺乳动物卵母细胞在胎儿卵巢开始减数分裂，但只有在成年生殖道受精后才能完成。这项审查审查了这一长期过程的细胞生物学：从原始生殖细胞进入减数分裂到受孕。减数分裂的定义特征是两个连续的细胞分裂（减数分裂I和II）和两个细胞周期停滞：在生小泡（GV），前期I的有毛ate期和中期II。这些逮捕涉及三个关键事件，这是本次审查的重点：（i）在视黄酸的调节下，胎儿生命期间从有丝分裂过渡到GV逮捕； （ii）受精后通过减数分裂I和（iii）完成减数分裂II，两个减数分裂分裂均受细胞周期蛋白依赖性激酶（CDK1）活性的调节。人类卵母细胞中的减数分裂I与年龄相关的染色体错分离率较高，例如21三体综合征（唐氏综合症），导致非整倍体概念使用。尽管非整倍性可能是多因素的，但由于将染色体结合在一起的凝聚力长期下降，因此老年妇女的卵母细胞可能倾向于变成非整倍性。减数分裂I期间卵母细胞无法检测到这种损失，这是因为其响应和阻断分裂的能力也会随着年龄的增长而恶化，或者是由于天生固有地无法对内聚力损失引起的分离缺陷类型做出反应。

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  • 来源
    《Human Reproduction Update》 |2008年第2期|p.143-158|共16页
  • 作者

    Keith T. Jones1;

  • 作者单位

    Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle, Framlington Place, Newcastle, NE2 4HH, UK;

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