First-meiotic-division nondisjunction in human oocytes
First-meiotic-division nondisjunction in human oocytes
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DOI：
10.1086/513890
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发表时间：
1997-07-01
影响因子：
9.8
通讯作者：
Angell, R
中科院分区：
文献类型：
--
作者：
Angell, R
体外受精患者的排斥卵母细胞是目前用于女性减数分裂研究的唯一实用的人类卵母细胞材料来源。本文对来自116例患者的200个可明确分析的二次减数分裂中期卵母细胞进行了检查，以寻找首次减数分裂错误的证据。染色体结果显示，67%的卵母细胞有正常的23x染色体补体，但没有一个卵母细胞有一条额外的完整染色体，这使人们对人类卵母细胞不分离理论的相关性产生了怀疑，这些理论认为二价染色体的两条染色体在MI时都不能分离，因此它们都移动到一个极点，并在MI中期产生一条额外的完整染色体。在MII卵母细胞中发现的唯一一类异常是单个染色单体（半染色体）取代整个染色体。对染色体异常卵母细胞的分析显示，在染色体分布、频率和母亲年龄方面，染色体异常与自然流产的三体数据密切相关，并表明染色单体异常可能是导致受精后三体形成的mi分裂非分离产物。最可能的异常来源是通过一种通常与单价染色体相关的分裂过程，在这种分裂过程中，着丝粒在MI而不是MII分裂时过早分裂。根据最近的数据显示，受影响染色体的重组模式改变是大多数mi分裂三体的一个关键特征，卵母细胞数据表明，由于重组模式改变而产生的脆弱减数分裂构型在老年妇女中被加工为功能性单价体。中期卵母细胞的初步证据支持这一观点。
Reject oocytes from in vitro-fertilization patients are currently the only practical source of human oocyte material available for meiotic studies in women. Two hundred clearly analyzable second meiotic (MII) metaphase oocytes from 116 patients were examined for evidence of first meiotic (MI) division errors. The chromosome results, in which 67% of oocytes had a normal 23,X chromosome complement but none had an extra whole chromosome, cast doubt on the relevance, to human oocytes, of those theories of nondisjunction that propose that both chromosomes of the bivalent fail to disjoin at MI so that both move to one pole and result in an additional whole chromosome at MII metaphase. The only class of abnormality found in the MII oocytes had single chromatids (half-chromosomes) replacing whole chromosomes. Analysis of the chromosomally abnormal oocytes revealed an extremely close correlation with data on trisomies in spontaneous abortions, with respect to chromosome distribution, frequency, and maternal age, and indicated the likelihood of the chromatid abnormalities being the MI-division nondisjunction products that lead to trisomy formation after fertilization. The most likely derivation of the abnormalities is through a form of misdivision process usually associated with univalents, in which the centromeres divide precociously at MI, instead of MII, division. In the light of recent data that show that altered recombination patterns of the affected chromosomes are a key feature of most MI-division trisomies, the oocyte data imply that the vulnerable meiotic configurations arising from altered recombination patterns are processed as functional univalents in older women. Preliminary evidence from MI-metaphase oocytes supports this view.