Chapter category: Reproductive Biology
Chromosome Abnormalities in Human Oocytes: Their Role in Reproductive Failure
Cytogenetics in Reproductive Medicine
Edited by: Dagan WellsISBN: 1-58706-205-4
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Chapter authors:
Michelle Plachot
Chromosome number abnormalities are remarkably common in human reproduction, as a consequence of both whole chromosome nondisjunction and premature chromatid separation during oocyte meiosis I. Pooled data from previous studies suggests that one in five oocytes that fail to fertilize after in vitro insemination are abnormal as assessed by conventional cytogenetics. FISH analysis of polar bodies has provided interesting additional data regarding the incidence of aneuploidy because it reveals both first and second meiotic errors. Indeed, preconception genetic diagnosis on more than 8000 oocytes showed that the rate of aneuploidy was as high as 52.1% in women aged 35 or over, mostly due to chromatid errors. Maternal aging is indeed a major factor affecting the frequency of aneuploidy in female gametes, although the biological mechanisms underlying this phenomenon are poorly understood. Oocyte dysmorphy seems to have little effect on the rate of aneuploidy. However, intra- and extrafollicular influences (perifollicular microvasculature, oxygenation, the presence of residues from cigarette smoke) may disturb maturation, leading to immaturity and aneuploidy. Thus, oocyte meiosis is very sensitive to endogenous and exogenous factors—these factors may cause the production of oocytes with chromosomal abnormalities and therefore abnormal zygotes. Abnormal zygotes may fail to implant leading to reduced fertility or failed IVF attempts, while those that form a pregnancy may ultimately cause a miscarriage or result in children with severe congenital abnormalities.
Additional chapters from this book:
Cytogenetics of Human Preimplantation Embryos
J.D.A. Delhanty* and D. Wells
Chromosomal abnormalities are common at all stages of human development and are the main cause of lethality between conception and birth. In natural conceptions the fecundity rate is about 25% w...
Uterine Leiomyomata: Aspects in Reproduction, Susceptibility, and Tumor Cytogenetics
Jennelle C. Hodge and Cynthia C. Morton
Uterine leiomyomata (UL), commonly referred to as fibroids, are the most frequent neoplasm of the female genital tract with such high morbidity as to account annually for one-third of hysterecto...
Preimplantation Genetic Diagnosis (PGD): Screening for Aneuploidy in Human Oocytes and Polar Bodies
J. Navarro,* C. Gutierrez-Mateo, A. Pujol, M. Durban, J.F. Sanchez-Garcia, J. Egozcue and J. Benet
Since it has been reported that in humans 90% of embryos are aneuploid as a result of malsegregation mechanisms in maternal meiosis I,1 the detection of abnormal oocytes in IVF treatments has become...
Cytogenetics of Human Sperm
Renee H. Martin
Constitutional chromosome abnormalities are seen frequently in infertile men. The consequences of these abnormalities in sperm are outlined. Infertile men with a normal chromosome karyotype also hav...
Rapid Prenatal Diagnosis of Common Chromosome Aneuploidies by Quantitative Fluorescent PCR
Vincenzo Cirigliano and Matteo Adinolfi
Prenatal diagnoses of chromosome abnormalities are performed by cytogenetic analyses of metaphase chromosomes obtained from fetal cells after several days of in vitro culture. The main disadvan...
Chromosome Abnormalities in Human Oocytes: Their Role in Reproductive Failure
Michelle Plachot
Chromosome number abnormalities are remarkably common in human reproduction, as a consequence of both whole chromosome nondisjunction and premature chromatid separation during oocyte meiosis I. ...
Prenatal Detection of Chromosome Abnormalities
Brynn Levy and Nataline Kardon
Chromosome abnormalities have been diagnosed from prenatal specimens for almost 40 years. In the United States, the current standard of care in obstetrical practice is to offer either chorionic ...
Chromosome Abnormalities in Spontaneous Abortions
Brynn Levy, Kurt Hirschhorn and Nataline Kardon
Most chromosome abnormalities lead to fetal loss, with the majority of losses occurring very early in gestation. The greater the size of the chromosomal aberration (imbalance), the earlier the f...
