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Updated: Jan 5, 2026

Preparation of Meiotic Chromosome Spreads from Mouse Oocytes for Assessment of Synapsis and Recombination
Published on: July 18, 2025
Chromosome errors in human eggs shape natural fertility over reproductive life span
Jennifer R Gruhn1, Agata P Zielinska2, Vallari Shukla1
1DNRF Center for Chromosome Stability, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
None:
Chromosome errors, or aneuploidy, affect an exceptionally high number of human conceptions, causing pregnancy loss and congenital disorders. Here, we have followed chromosome segregation in human oocytes from females aged 9 to 43 years and report that aneuploidy follows a U-curve. Specific segregation error types show different age dependencies, providing a quantitative explanation for the U-curve. Whole-chromosome nondisjunction events are preferentially associated with increased aneuploidy in young girls, whereas centromeric and more extensive cohesion loss limit fertility as women age. Our findings suggest that chromosomal errors originating in oocytes determine the curve of natural fertility in humans.
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