Figure 6. Schematic representation for loss of chromosome cohesion and the generation of single chromatids in MII oocytes as a result of maternal aging. The effect of advanced maternal age is depicted on a bivalent (dark and light blue) during meiosis I. Aging is associated with weakened cohesion (red rings). The increased distance between sister chromatid kinetochores prevents them from working as a single unit. They are therefore subject to random segregation, as opposed to equal segregation.