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Updated: Aug 3, 2026
11:13
Using Mouse Oocytes to Assess Human Gene Function During Meiosis I
Published on: April 10, 2018
Relationship between embryo quality and aneuploidies
V Baltaci1, H Satiroglu, C Kabukçu
1GenArt Women's Health and Reproductive Biotechnology Centre, Cinnah Street 47/A Cankaya, Ankara, Turkey. baltacivolkan@yahoo.com
Reproductive Biomedicine Online
|February 4, 2006
Summary
Embryo quality does not always predict genetic health. Preimplantation genetic diagnosis (PGD) revealed that even high-grade embryos can have chromosomal abnormalities, impacting infertility treatments.
Area of Science:
- Reproductive Medicine
- Genetics
- Embryology
Background:
- Morphological assessment is a standard method for selecting embryos for transfer.
- Chromosomal abnormalities (aneuploidy) are a significant cause of implantation failure and miscarriage.
- Preimplantation genetic diagnosis (PGD) screens embryos for aneuploidy before transfer.
Purpose of the Study:
- To investigate the correlation between embryo morphological grade and chromosomal status.
- To determine if embryo quality is a reliable indicator of euploidy.
Main Methods:
- Multicolour fluorescence in-situ hybridization (FISH) was used to analyze chromosomes 13, 18, 21, X, and Y.
- PGD was performed on 1107 embryos from 132 patients.
- Statistical analysis was conducted to assess the relationship between embryo grade and aneuploidy.
Main Results:
- A significant relationship was found between PGD results and embryo morphological grades (P = 0.001).
- Euploidy was positively correlated with higher embryo grades (P = 0.001).
- A considerable proportion of both normal (50.7%) and aneuploid (36.1%) embryos were classified as grade I.
Conclusions:
- Embryo morphological grade alone is not a sufficient predictor of chromosomal normality.
- Chromosomally abnormal embryos can exhibit good morphology and developmental potential.
- PGD is crucial for accurate embryo selection to improve infertility treatment outcomes.
Related Concept Videos
01:49Meiosis I
Meiosis is a carefully orchestrated set of cell divisions, the goal of which—in humans—is to produce haploid sperm or eggs, each containing half the number of chromosomes present in somatic cells elsewhere in the body. Meiosis I is the first such division, and involves several key steps, among them: condensation of replicated chromosomes in diploid cells; the pairing of homologous chromosomes and their exchange of information; and finally, the separation of homologous chromosomes by a...
02:07Oogenesis
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...
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...
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...
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...