Oocytes present at birth are the ones eventually ovulated for fertilization. Therefore, the aging of mammalian oocytes is coupled with the aging of the females. Oocytes of aged females encounter longer exposures to different damaging agents present in the ovarian microenvironment, such as reactive oxygen species (ROS).
Consequently, age-related effects might be exacerbated in oocytes compared with other somatic cells. For example, human oocytes from older women have significantly higher rates of chromosomal abnormalities than those from younger women. Similarly, in female macaques, there is a significant increase in the frequency of aneuploid oocytes and aneuploid conceptuses with maternal aging, suggesting an increased risk of transmitting defective gametes to offspring.
