Female reproductive aging is accompanied by high incidence of aneuploidy in eggs. Despite decades of investigation, the molecular origins of age-related egg aneuploidy remain a mystery. In a newly published paper, the Mogessie lab shows that spindle actin, a machinery that is unique to reproductive cells, prevents chromosomal abnormalities in eggs of reproductively older females. Using advanced microscopy and rapid protein degradation technologies, they have found that age-dependent loss of spindle actin apparatus predisposes mammalian eggs to aneuploidies that are broadly associated with miscarriages, infertility and birth-related genetic disorders. This discovery provides new insights into cellular architectures that underpin female reproductive longevity.