Pellestor F, Anahory T, Hamamah S
CNRS UPR 1142, Institute of Human Genetics, 141 rue de la Cardonille, F-34396 Montpellier Cedex 5, France.
Hum Reprod Update. 2005 Jan-Feb;11(1):15-32. doi: 10.1093/humupd/dmh051. Epub 2004 Nov 29.
The cytogenetic survey of mature human oocytes has been and remains a subject of great interest because of the prevalence of aneuploidy of maternal origin in abnormal human conceptuses, and the lack of understanding about the non-disjunction processes in human meiosis. The first attempts to analyse the chromosomal content of human female gametes were made in the early 1970s, and led to limited data because of the paucity of materials and the inadequacy of the procedure used. The years to follow brought a resurgence of interest in this field, because of the development of human IVF techniques which made oocytes unfertilized in vitro available for cytogenetic analysis. Numerous studies have since been performed. However, the difficulties in obtaining good chromosome preparations and of performing accurate chromosome identification have reduced the viability of these studies, resulting in large variations in the reported incidences of chromosomal abnormalities. The further introduction of new procedures for oocyte fixation and the screening of large oocyte samples have allowed more reliable data to be obtained and to identify premature chromatid separation as a major mechanism in aneuploidy occurrence. The last decade has been privileged to witness the adaptation of molecular cytogenetic techniques to human oocytes, and thus various powerful procedures have been tried not only on female gametes, but also on polar bodies, involving sequential and multicolour fluorescent in situ hybridization (FISH) labelling, comparative genomic hybridization (CGH), spectral karyotyping and alternative methods such as primed in situ labelling (PRINS) and peptide nucleic acid (PNA) techniques. A large body of data has been obtained, but these studies also display a great variability in the frequency of abnormalities, which may be essentially attributable to the technical limitations of these in situ methods when applied to human oocytes. However, molecular cytogenetic approaches have also evidenced the co-existence of both whole chromosome non-disjunction and chromatid separation in maternal aneuploidy. In addition, the extension of these techniques to oocyte polar body materials has provided additional data on the mechanism of meiotic malsegregation. Improvements of some of these techniques have already been reported. The further development of new approaches for the in situ analysis of human meiosis will increase the impact of cytogenetic investigation of human oocytes in the understanding of aneuploidy processes in humans.
由于人类异常妊娠中母源非整倍体的普遍存在，以及对人类减数分裂中不分离过程缺乏了解，成熟人类卵母细胞的细胞遗传学研究一直是且仍然是一个备受关注的课题。20世纪70年代初首次尝试分析人类雌性配子的染色体组成，但由于材料匮乏和所用方法的不足，所得数据有限。随后的几年里，由于人类体外受精技术的发展，使得体外未受精的卵母细胞可用于细胞遗传学分析，该领域重新引起了人们的兴趣。此后进行了大量研究。然而，获得良好染色体标本以及进行准确染色体鉴定的困难降低了这些研究的可行性，导致所报道的染色体异常发生率差异很大。卵母细胞固定新方法的进一步引入以及对大量卵母细胞样本的筛查，使得能够获得更可靠的数据，并确定过早染色单体分离是导致非整倍体发生的主要机制。过去十年有幸见证了分子细胞遗传学技术应用于人类卵母细胞，因此各种强大的方法不仅在雌性配子上进行了尝试，也在极体上进行了尝试，包括顺序和多色荧光原位杂交（FISH）标记、比较基因组杂交（CGH）、光谱核型分析以及诸如引物原位标记（PRINS）和肽核酸（PNA）技术等替代方法。已经获得了大量数据，但这些研究在异常频率方面也显示出很大的变异性，这可能主要归因于这些原位方法应用于人类卵母细胞时的技术局限性。然而，分子细胞遗传学方法也证明了在母源非整倍体中全染色体不分离和染色单体分离并存。此外，将这些技术扩展到卵母细胞极体材料，为减数分裂错误分离机制提供了更多数据。已经报道了其中一些技术的改进。人类减数分裂原位分析新方法的进一步发展将增加人类卵母细胞细胞遗传学研究在理解人类非整倍体过程中的影响力。
