Actin-Related Causes of Aneuploidy in Human Eggs.

Gametogenesis (oogenesis and spermatogenesis) relies on a specialized form of cell division known as meiosis. During this process, chromosomes in parental cells undergo two successive rounds of segregation, resulting in a halving of their number and the formation of haploid germ cells, which is essential for subsequent fertilization. However, in human female gametogenesis, errors in chromosome segregation occur at a notably high frequency, leading to the formation of oocytes with abnormal chromosome numbers. Once fertilized, such oocytes often develop into aneuploid embryos, which exhibit severely impaired developmental potential and frequently end in implantation failure or early pregnancy loss. Notably, with advancing maternal age, the frequency of errors in meiotic maturation mediated by the actin and microtubule cytoskeletons increases significantly, thereby elevating the overall risks of infertility, pregnancy termination, and birth defects such as Down syndrome. This article aims to systematically review recent advances in the mechanisms by which actin contributes to the formation of aneuploidy in female meiosis, with a particular focus on findings from human oocytes.