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Updated: Jun 24, 2026
12:11
Analysis of Chromosome Segregation, Histone Acetylation, and Spindle Morphology in Horse Oocytes
Published on: May 11, 2017
[Maternal age and chromosomal abnormalities in human oocytes].
1Institut de Génétique humaine, CNRS UPR 1142, 141, rue de la Cardonille, 34396 Montpellier Cedex 5, France. franck.pellestor@igh.cnrs.fr
Medecine Sciences : M/S
|August 27, 2004
Summary
Maternal aging increases aneuploidy risk due to premature chromatid separation during meiosis. This study links age-related changes in chromatid cohesion to nondisjunction events in human oocytes.
Area of Science:
- Reproductive Biology
- Human Genetics
- Cell Biology
Context:
- Maternal age is a primary risk factor for aneuploid conceptuses.
- Previous research highlighted recombination patterns in trisomy occurrence.
- A comprehensive chromosomal study was needed to investigate age-related nondisjunction mechanisms.
Purpose:
- To investigate the relationship between maternal age and numerical chromosomal abnormalities in human oocytes.
- To identify the specific meiotic errors contributing to age-dependent aneuploidy.
- To elucidate the role of chromatid cohesion in female meiotic nondisjunction.
Summary:
- A study of 1,397 unfertilized human oocytes revealed that maternal age correlates with whole chromosome nondisjunction and premature chromatid separation.
- Premature chromatid separation showed the strongest correlation with maternal age, leading to free chromatids in metaphase II oocytes.
- These findings indicate that impaired chromatid cohesion, potentially involving cohesins, is a key factor in age-related aneuploidy during female meiosis.
Impact:
- Provides novel insights into the mechanisms underlying age-dependent aneuploidy in female meiosis.
- Suggests that disturbances in molecular chromatid cohesion are critical in maternal age effect.
- Offers potential targets for understanding and possibly mitigating age-related reproductive risks.
Related Concept Videos
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01:29Nondisjunction
During meiosis, chromosomes occasionally separate improperly. This occurs due to failure of homologous chromosome separation during meiosis I or failed sister chromatid separation during meiosis II. In some species, notably plants, nondisjunction can result in an organism with an entire additional set of chromosomes, which is called polyploidy. In humans, nondisjunction can occur during male or female gametogenesis and the resulting gametes possess one too many or one too few chromosomes.
03:09Meiosis I
Meiosis is the division of a diploid cell into haploid cells forming sperm and eggs in animals through differentiation. Meiosis I is the first stage of meiosis, where the genetic recombination of homologous chromosomes and the reduction of the ploidy level by half occurs.
Prophase I is the most extended and complex step of meiosis I characterized by synapsis, chromosome pairing, and recombination of the homologous chromosomes. This process is facilitated by a proteinaceous structure called the...
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02:57Meiosis vs. Mitosis
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Before the start of mitosis and meiosis I, the cell synthesizes DNA, resulting in two homologous copies of each chromosome. DNA synthesis is...
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01:21Nondisjunction
Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate correctly and move to the opposite poles of the cells. This produces daughter cells with abnormal chromosome numbers. Nondisjunction is common during anaphase I or anaphase II of meiosis. Mutations in synaptonemal complex proteins that attach homologous chromosomes increase the chances of nondisjunction in anaphase I of meiosis I. In contrast, mutations in topoisomerases and condensins that hold sister...
01:22Oogenesis
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Each primary oocyte is surrounded by a layer of pre-granulosa cells, forming what is known...
Each primary oocyte is surrounded by a layer of pre-granulosa cells, forming what is known...