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Chromosome studies in oocytes and zygotes from an IVF programme
A Veiga1, G Calderón, J Santaló
1Departament de Ginecologia i Obstetricia, Institut Dexeus, Barcelona, Spain.
Human Reproduction (Oxford, England)
|July 1, 1987
Summary
Chromosome abnormalities in human oocytes and zygotes can lead to aneuploidy and polyploidy. Our IVF study found 26.5% of oocytes and zygotes had chromosomal issues, impacting viability.
Area of Science:
- Human embryology
- Reproductive genetics
- In vitro fertilization (IVF)
Background:
- Chromosome abnormalities in oocytes and zygotes are a significant cause of infertility and implantation failure.
- Understanding the incidence and types of these aberrations is crucial for improving IVF outcomes.
Purpose of the Study:
- To investigate the frequency and nature of chromosome abnormalities in oocytes and zygotes within an IVF program.
- To identify potential sources of error in assessing zygote ploidy.
Main Methods:
- Karyotyping of 117 oocytes, 17 one-cell zygotes, and 4 two- to four-cell zygotes.
- Analysis of chromosome number, ploidy status, and structural aberrations.
- Examination of pronuclear morphology and polar body extrusion.
Main Results:
- Aneuploidy was observed in 15.4% of unfertilized oocytes.
- Incidence of unreduced oocytes (due to first polar body retention) was 6.8%.
- Total incidence of potentially aneuploid, polyploid, or non-viable zygotes due to oocyte chromosome aberrations was 26.5%.
Conclusions:
- A significant proportion of oocytes and zygotes in IVF exhibit chromosome abnormalities.
- Misinterpretation of pronuclei or cytoplasmic structures can affect ploidy assessment.
- Oocyte-derived chromosomal aberrations contribute substantially to zygote aneuploidy and polyploidy, impacting IVF success rates.