From Cytoskeletal Remodeling to Oocyte Quality: The Emerging Role of Mechanics.

Oocyte quality is essential for successful fertilization and embryonic development. At the end of mammalian oogenesis, oocytes undergo two highly asymmetric meiotic divisions that preserve maternal reserves while generating a haploid gamete. These divisions rely on dynamic cytoplasmic and cortical actomyosin networks. The mechanical properties of the oocyte, shaped by the remodeling of these networks, are critical regulators of oocyte morphogenesis, controlling cytoplasmic organization, spindle positioning, chromosome segregation, and cytokinesis. Meiotic errors, which increase with maternal age, compromise fertility and embryonic development. In parallel, the growing use of assisted reproductive technologies, including oocyte freezing for fertility preservation, has intensified the need for reliable markers of oocyte quality. Beyond conventional morphological assessment, oocyte mechanical properties have recently emerged as promising indicators of developmental competence, as naturally occurring mechanical defects can impair oocyte quality. This review discusses the molecular and cellular pathways regulating oocyte mechanics in relation to actomyosin reorganization, their roles during oocyte divisions, their alteration in pathological contexts, and their potential clinical applications as markers in reproductive medicine.