For women, the biological clock starts ticking by their mid-30s at the latest: Fertility decreases, the risk of miscarriages increases. One of the main reasons behind both are eggs with altered chromosome numbers. It has remained largely unclear, however, why eggs from older women more frequently possess too many or too few chromosomes. A German-English research team has now discovered that certain structures on the egg’s chromosomes age and fall apart, possibly promoting incorrect chromosome distribution.
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