Oocyte aging: cellular and molecular changes, developmental potential and reversal possibility.
BACKGROUND
In humans, normal healthy children are regularly produced through fertilization of fresh oocytes with fresh spermatozoa. However, asynchrony between oocytes and spermatozoa, especially when aged oocytes are fertilized by fresh or senescent spermatozoa, will not only affect the rate of fertilization and pre- and post-implantation embryo development but also the life of the offspring. As many failures in assisted reproduction technologies (ART) are related to oocyte aging, new methods are needed to control oocyte aging to benefit modern ART.


METHODS
We review changes associated with decreased fertilization rates and developmental potential of aged oocytes, and we present methods and approaches that prevent or delay oocyte aging.


RESULTS
Cellular and molecular abnormalities occur during oocyte aging, but prevention, delay or reversal is possible to various extents. Modifying existing culture conditions, or treatment of oocytes with agents such as caffeine, DL-dithiothreitol, nitric oxide or trichostatin A may correct molecular pathways that are affected by aging, and thus benefit and improve success rates in modern ART.


CONCLUSIONS
Aging of oocytes is characterized by a sequence of molecular processes that deteriorate during aging and negatively impact fertilization and development. However, oocyte aging can be delayed or reversed by various treatments to increase success rates and produce increased numbers of healthy embryos, preventing failures or abnormalities that are frequently associated with ART using aged oocytes.
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China.
Yi-Liang
YL
Miao
Kazuhiro
K
Kikuchi
Qing-Yuan
QY
Sun
Heide
H
Schatten
D000818:Animals; D017209:Apoptosis; D020013:Calcium Signaling; D016922:Cellular Senescence / Q000235:genetics / Q000502:physiology*; D054885:Cumulus Cells / Q000502:physiology; D047108:Embryonic Development; D044127:Epigenesis, Genetic; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D008297:Male; D008954:Models, Biological; D009865:Oocytes / Q000166:cytology* / Q000254:growth & development / Q000502:physiology*; D011247:Pregnancy; D017382:Reactive Oxygen Species / Q000378:metabolism; D027724:Reproductive Techniques, Assisted
D017382:Reactive Oxygen Species