A New Technique for the Cytogenetic Study of Human Oocytes (original) (raw)
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Chromosomal analysis of unfertilized human oocytes prepared by a gradual fixation-air drying method
Human Genetics, 1993
Two hundred and sixty-five unfertilized human metaphase II (M II) oocytes from an in vitro fertilization program were studied cytogenetically using our chromosomal technique, a gradual fixation-air drying method. Of the 265 oocytes, 185 (70%) were successfully karyotyped. There were 21 aneuploids (11.4%) consisting of 8 hyperhaploids (4.3%), 11 hypohaploids (5.9%) and 2 complex cases (1.1%). There were also 9 structural anomalies (4.9%) and 18 diploids (9.7%). In aneuploidy, the loss or gain of dyads (so-called nondisjunction) occurred more frequently than the loss or gain of monads (so-called predivision). The frequency of abnormally behaved chromosomes (segregation errors) due to nondisjunction, anaphase lag and predivision was studied among the seven chromosomal groups (A-G) and compared with the frequency expected from an equal probability of segregation errors in each of the 23 chromosomes. The observed frequency was somewhat higher than the expected frequency in groups E and G but the difference was not statistically significant in either group. These results were discussed in relation to previous studies on human M II oocyte chromosomes.
Cytogenetics of unfertilized human oocytes
Reproduction, 1988
During an in-vitro fertilization programme 150 oocytes from 62 women with a mean age of 31 years (range 24-39) remained unfertilized. Successful chromosome analysis was carried out on 96 oocytes by Q-banding: 59 (61.5%) oocytes bore a normal haploid complement, 8 (8.3%) were diploid and 3 (3.1%) tetraploid. In 26 (27.1%) oocytes aneuploidy was observed; these included 9 (9.4%) nullisomic, 5 (5.2%) double nullisomic, 4 (4.2%) triple nullisomic and 2 (2.1%) disomic oocytes. The remaining 54 (36.0%) oocytes could not be evaluated. A nearly uniform rate of aneuploidy was found for unfertilized oocytes among different donor age groups.
Human Reproduction, 1998
The incidence of chromosomal abnormalities was studied in 719 unfertilized human oocytes obtained from our invitro fertilization (IVF) programme. To make chromosome preparations, a gradual fixation/air-drying method was utilized. Of 388 oocytes successfully karyotyped, 70 (18.0%) were abnormal. The abnormalities included 33 aneuploidies (8.5%) (14 hyperhaploidies and 19 hypohaploidies), 25 diploidies (6.4%) and 15 structural abnormalities (3.9%), three of them being accompanied by aneuploidy. Of the 33 aneuploidies, 16 (48.5%) showed the loss or gain of dyads (so-called non-disjunction), while 17 (51.5%) showed the loss or gain of monads (so-called predivision). There was no maternal age-dependent increase in the incidence of aneuploidy. Unfertilized oocytes from patients with a high fertilization rate (>25%) had a significantly higher (11.4%, P < 0.05) incidence of diploidy compared with the oocytes from the remaining patients (4.3 and 4.0%), suggesting that diploid oocytes might have a lower fertilizing ability.
Chromosomal FISH analysis of unfertilized human oocytes and polar bodies
Journal of Human Genetics, 2002
The incidence of chromosomal aneuploidy was studied in 208 unfertilized metaphase II human oocytes from an in vitro fertilization program by fluorescence in situ hybridization using probes for chromosomes 18, 21, and X. Chromosome spreads were prepared by a gradual fixationair-drying method. We obtained analyzable results from 183 oocytes and 93 polar bodies; 167 oocytes (91%) were normal, 11 (6%) were diploid, and 5 (3%) were aneuploid. Of the five aneuploid oocytes, four involved chromosome 21, and one involved the X chromosome. In this study, oocyte aneuploidy caused by both nondisjunction of bivalent chromosomes and predivision of univalent chromosomes was observed. The aneuploidy rate (9.8%) in the oocytes from women aged м35 years was significantly higher than that (0.7%) in those aged 23 to 34 years (P ϭ 0.0017).
Whole-Chromosome Aneuploidy Analysis in Human Oocytes: Focus on Comparative Genomic Hybridization
Cytogenetic and Genome Research, 2011
The study of aneuploidy in human oocytes, discarded from IVF cycles, has provided a better understanding of the incidence of aneuploidy of female origin and the responsible mechanisms. Comparative genomic hybridization (CGH) is an established technique that allows for the detection of aneuploidy in all chromosomes avoiding artifactual chromosome losses. In this review, results obtained using CGH in single cells (1PB and/or MII oocytes) are included. The results of oocyte aneuploidy rates obtained by CGH from discarded oocytes of IVF patients and of oocyte donors are summarized. Moreover, the mechanisms involved in the aneuploid events, e.g. whether alterations occurred due to first meiotic errors or germ-line mitotic errors are also discussed. Finally, the incidence of aneuploid oocyte production due to first meiotic errors and germ-line mitotic errors observed in oocytes coming from IVF patients and IVF oocyte donors was assessed.
Journal of In Vitro Fertilization and Embryo Transfer, 1990
In vitro fertilization cycles yield a low percentage of pregnancies, Eighty-five to ninety percent of the transferred embryos do not implant, and the abortion rate approaches 30%. Aneuploidy is assumed to be responsible for a major portion of this pregnancy wastage. The purpose of this study was to determine if there was any correlation between morphology and chromosomal content of unfertilized oocytes and rejected embryos. To assess the chromosomal content of oocytes and embryos, we used the method described by Tarkowsld in 1966. Sixty oocytes from 28 women, aged between 27 and 41 years, were analyzed. Sixty-seven percent were aneuploid; of these, 23.35% were hyperhaploid, 23.35% were hypohaploid, 8.35% were hyperdiploid, 3.35% were diploid, and 8.35% showed premature chromosome condensation. Of 20 preimplantation embryos analyzed, 80% were aneuploid, 10% were diploid, 5% were haploid, and 5% showed structural anomaly. Correlation was found between maternal age and aneuploidy in oocytes and between morphology and genetic balance in preimplantation embryos.
Journal of In Vitro Fertilization and Embryo Transfer, 1985
Chromosomal abnormalities and abnormal embryonic development have previously been observed after human in vitro fertilization (IVF). Chromosomal abnormalities may arise not only after fertilization but even earlier during meiotic maturation of human ooeytes in culture. Since chromosomal analysis is simple in oocytes during meiotic maturation, the chromosomal status was analyzed in oocytes which remained unfertilized in a human in vitro fertilization program. In 50fertilization attempts the chromosomes of 62 unfertilized oocytes could be analyzed; 45 of them were in the process of meiotic maturation. In three oocytes two small polar bodies were observed 16-18 hr after insemination in the absence offertilization. In one oocyte abnormal chromosome behavior was found during the first meiotic division, and in four oocytes during metaphase of the second meiotic division. These data suggest that chromosomal analysis of unfertilized oocytes in human IVF may improve the understanding of human oocyte maturation and fertilization.
FISH analysis of six chromosomes in unfertilized human oocytes after polar body removal
Journal of assisted reproduction and genetics, 2000
To develop an improved technique for estimating chromosomal abnormalities in human oocytes by fluorescence in situ hybridization (FISH) and to correlate the position of single chromatids with the chromosomal status of the oocytes. Oocytes that were at metaphase II about 17-20 hr after insemination or intracytoplasmic sperm injection (ICSI) were treated with pronase to remove the zona pellucida and polar body (PB) and then spread on slides using HCl and Tween 20. Two rounds of FISH were performed using direct-labeled probes: chromosomes 1, 13, 21 (round 1); chromosomes X, 7, 18 (round 2). Of the 63 oocytes from 18 patients (mean age, 32 years), 48 (76%) had one DNA complement as expected, 9 (14%) had 2 DNA complements, 3 (5%) gave incomplete FISH signals, and 3 (5%) were not analyzable. Of the 48 oocytes with one set of DNA, 48% were haploid, 44% were aneuploid for one or more chromosomes, and 8% were polyploid. We also found an increased frequency of predivision of chromatid bivalen...
European Journal of Human Genetics, 2003
We used fluorescent in situ hybridisation (FISH) to detect nine chromosomes and X) in 89 first Polar Bodies (1PBs), from in vitro matured oocytes discarded from IVF cycles. In 54 1PBs, we also analysed the corresponding oocyte in metaphase II (MII) to confirm the results; the other 35 1PBs were analysed alone as when preimplantation genetic diagnosis using 1PB (PGD-1PB) is performed. The frequency of aneuploid oocytes found was 47.5%; if the risk of aneuploidy for 23 chromosomes is estimated, the percentage rises to 57.2%. Missing chromosomes or chromatids found in 1PBs of 1PB/MII doublets were confirmed by MII results in 74.2%, indicating that only 25.8% of them were artefactual. Abnormalities observed in 1PBs were 55.8% whole-chromosome alterations and 44.2% chromatid anomalies. We observed a balanced predivision of chromatids for all chromosomes analysed. Differences between balanced predivision in 1PB and MII were statistically significant (Po0.0001, v 2 test); the 1PB was most affected. The mean abnormal segregation frequency for each chromosome was 0.89% (range 0.52-1.70%); so, each of the 23 chromosomes of an oocyte has a risk of 0.89% to be involved in aneuploidy. No significant differences were observed regarding age, type of abnormality (chromosome or chromatid alterations) or frequency of aneuploidy. Nine of the 35 patients (25.7%) whose 1PB and MII were studied presented abnormalities (extra chromosomes) that probably originated in early oogenesis. Analysis of 1PBs to select euploid oocytes could help patients of advanced age undergoing in vitro fertilization (IVF) treatment.