News from the secret world of the egg cell

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 ex...