Figure 7.
Schematic representation of the involvement of increased pHi in aneuploidy in old oocytes. Aging causes decreased HCO3−/Cl− exchanger activity in full-grown GV oocytes, which have the strongest HCO3−/Cl− exchanger activity of the oocyte phases.26,27 Therefore, in subsequent phases of aged oocytes, anions cannot be excluded in a timely manner to the extracellular compartment due to reduced activity of the HCO3−/Cl− exchanger, leading to an increase in the oocyte pHi. The increased pHi of aged oocytes might affect the cohesin subunit-subunit binding affinity, change its stability, modify its function, and alter its subcellular localization, among other effects. Finally, the increased pHi of aged oocytes gives rise to the deterioration of the cohesin wrapped around the chromosome, leading to increased aneuploidy. The small blue circle represents the nucleus, and the pink circle represents the cytoplasm.