Human eggs often contain the wrong number of chromosomes, leading to miscarriages and infertility. A research team led by Melina Schuh at the Max Planck Institute (MPI) for Multidisciplinary Sciences has discovered that human eggs are missing an important protein, which acts as a molecular motor. This motor helps to stabilize the machinery that separates the chromosomes during cell division. The researchers’ findings open up new avenues for therapeutic approaches that could reduce chromosome segregation errors in human eggs.