Oocyte aging: cellular and molecular changes, developmental potential and reversal possibility

Abstract

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.

Correlation of oocyte morphometry parameters with woman’s age

“…It is well known that oocyte aging is one of the most important factors involved in the failure of the assisted reproduction techniques. Oocyte aging has been associated with several morphological and functional alterations, including changes in structure of the plasma membrane, zona pellucida, cytoskeleton or mitochondria, displacement of the spindle, misalignment of chromosomes, dispersion of centrosomal material, displacement of first polar body and cortical granules [29]. Our results clearly show that aged oocytes are characterized by thinner zonae and a reduced total and cytoplasm diameter.…”

Actin cytoskeleton in cell polarity and asymmetric division during mouse oocyte maturation

“…This site of cortical polarization marks the position for polar body extrusion, which depends on cortical cytoskeleton reorganization. Defects in asymmetric spindle positioning or cortical polarization lead to several abnormalities including equally divided oocytes or polyploid eggs, as commonly seen in individuals of increased maternal age Kim et al, 1996;Miao et al, 2009].…”

Epigenetic changes associated with oocyte aging

“…Previously, we and others have fully reviewed the cellular and molecular alterations as well as the mechanisms underlying oocyte aging [1, 2,6,7]. The protein profiles during porcine oocyte aging have also been investigated by us [30].…”

“…If fertilization does not occur within that time range, unfertilized oocytes remaining in the oviduct (in vivo aging) or culture (in vitro aging) will undergo a time-dependent deterioration in quality, a process called "oocyte aging". "Aged oocytes" are those oocytes in which aging already has occurred but not to the extent of degeneration [5,6]. On the other hand, with increasing age oocytes in the ovary suffer from progressive decline of quality and decrease in developmental potential.…”