Oocyte competence: A systematic review of omics studies and the state of art

Competent oocyte is a critical point for successful fertilization and early embryonic development. This systematic review aimed to synthesize scientific evidence from omics studies on oocyte development in cattle during the estrous cycle. Our systematic search followed the PRISMA guidelines, using three databases: PubMed, Scopus, and Web of Science Core Collection. After a critical appraisal of the literature using the Kmet scoring system, ten peer-reviewed articles were included. These studies involved analyses of follicular fluid, cumulus and granulosa cells, oocytes, and maturation media. Transcriptomics predominated among the studies and identified transcriptional patterns associated with oocyte competence in different cell types and stages of the estrous cycle, particularly around the LH surge. In addition, experiments focusing on the ovulatory window as the main theme were identified in the studies. Metabolomic analyses highlighted the role of amino acid turnover and purine metabolism in follicular fluid and maturation media, providing insights into potential biomarkers in oocyte development. The results emphasized the importance of nucleotide metabolism, extracellular matrix interactions, and hormonal signaling pathways, particularly involving genes such as INHBA, TNFAIP6, and TRIB2, in regulating oocyte maturation. This review underscores the power of integrating omics data to elucidate complex molecular mechanisms relevant to the acquisition of oocyte competence. Furthermore, it explores the identification of potential molecular markers that would aid the development of protocols and culture media, while aiming to improve oocyte quality and advance assisted reproductive technologies.