The division of mammalian egg cells depends on cohesin proteins that embrace chromosomes before birth and are not renewed thereafter, scientists have discovered. The cohesin complex is remarkably long-lived but eventually lost irreversibly from chromosomes. The inability of egg cells to renew the ties that hold chromosomes together might contribute to maternal age-related chromosome missegregation and aneuploidy, leading to the production of trisomic fetuses. These insights provide a possible explanation for the molecular causes of the maternal age effect.
Source: Medicine Science Daily