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Related Concept Videos

Oogenesis02:07

Oogenesis

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In human women, oogenesis produces one mature egg cell or ovum for every precursor cell that enters meiosis. This process differs in two unique ways from the equivalent procedure of spermatogenesis in males. First, meiotic divisions during oogenesis are asymmetric, meaning that a large oocyte (containing most of the cytoplasm) and minor polar body are produced as a result of meiosis I, and again following meiosis II. Since only oocytes will go on to form embryos if fertilized, this unequal...
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Oogenesis01:22

Oogenesis

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Oogenesis,  the process of developing egg cells (female gametes), occurs within the ovaries and is fundamental to female fertility. This sequence begins during fetal development when diploid oogonia in the developing ovaries undergo mitotic divisions to produce primary oocytes. By birth, these primary oocytes enter prophase I of meiosis but become arrested in this stage, remaining suspended until puberty.
Each primary oocyte is surrounded by a layer of pre-granulosa cells, forming what is...
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Nondisjunction01:21

Nondisjunction

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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...
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Nondisjunction01:29

Nondisjunction

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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.
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Meiosis vs. Mitosis02:57

Meiosis vs. Mitosis

66.3K
Cell division is necessary for growth and reproduction in organisms. Mitosis aids cell growth and development by dividing somatic cells. In contrast, meiosis causes the division of germ cells and plays an essential role in sexual reproduction. Due to their unique functional requirements, mitosis and meiosis differ from each other in multiple aspects.
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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Meiosis I03:09

Meiosis I

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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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Related Experiment Video

Updated: Nov 30, 2025

Mouse Oocyte Microinjection, Maturation and Ploidy Assessment
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Mouse Oocyte Microinjection, Maturation and Ploidy Assessment

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Why is oocyte aneuploidy increased with maternal aging?

Jun-Yu Ma1, Sen Li1, Lei-Ning Chen1

  • 1Fertility Preservation Lab, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, 510317, China.

Journal of Genetics and Genomics = Yi Chuan Xue Bao
|November 13, 2020
PubMed
Summary

Maternal aging increases oocyte aneuploidy, a cause of pregnancy failure. This review explores factors like spindle defects and oxidative stress, aiming to understand and prevent chromosome errors in aged eggs.

Keywords:
AgingAneuploidyCohesinDNA damageMeiosisMitochondriaOocyteSACSpindle

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Area of Science:

  • Reproductive Biology
  • Genetics
  • Cell Biology

Background:

  • Oocyte aneuploidy is a primary cause of pregnancy failure and fetal abortion.
  • The incidence of oocyte aneuploidy significantly increases with maternal aging.
  • Potential contributing factors include defects in recombination, chromosome segregation, and mitochondrial function.

Purpose of the Study:

  • To review and integrate current research on the causes of oocyte aneuploidy in aged oocytes.
  • To explore the interrelations between various aneuploidization factors.
  • To identify potential strategies for preventing chromosome aneuploidy in aging oocytes.

Main Methods:

  • Literature review of studies on oocyte aneuploidy and maternal aging.
  • Synthesis of proposed mechanisms contributing to aneuploidization.
  • Analysis of epidemiological associations with oocyte aneuploidy.

Main Results:

  • Multiple factors contribute to oocyte aneuploidy, including spindle assembly checkpoint malfunction, cohesin loss, and increased reactive oxygen species.
  • Epidemiological studies suggest weak associations with homocysteine, obesity, radiation, and seasonality.
  • The precise interconnections between these factors and effective prevention strategies remain under investigation.

Conclusions:

  • Oocyte aneuploidy in aged women is multifactorial, involving complex cellular and molecular processes.
  • Understanding these interconnected factors is crucial for developing interventions.
  • Further research is needed to elucidate causal relationships and establish preventative measures.