The markers of oocyte quality have remained a major controversy in the field of embryology due to the subjectivity of the different methods of oocyte assessment. Various scholars use oocyte quality and oocyte competence interchangeably. Oocyte quality can be defined as the overall health of an oocyte whereas oocyte competence refers to the ability of an oocyte to be fertilized and develop into a healthy embryo. Diminished oocyte quality is believed to be a result of alterations in oocyte growth and maturation processes that stem from several pelvic and systemic factors before and after oocyte retrieval. In this review, we focus on the morphological and nonmorphological markers of oocyte quality. Strict restrictions that limit the number of oocytes fertilized in various countries have triggered researchers around the world to come up with the most appropriate and noninvasive markers that enhance oocyte selection and optimize IVF outcomes. PubMed, Google Scholar, and the Cochrane Library were used to search for peer-reviewed, original articles about oocyte quality markers. The review was written in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Morphological markers are commonly used, but they are subjective, and no single marker can be used exclusively to predict oocyte competence and subsequent embryonic development potential. Furthermore, transcriptomics of differentially expressed genes in cumulus cells and assessment of metabolomics and other contents of follicular fluid have shown greater precision. However, their specificity to the different quality determinants needs further research.
Muhammad KayanjaMoses TiriMark MuyigoDavis RujumbaNyiro BrianKalule Francis
Omega-3 polyunsaturated fatty acids(n-3 PUFAs),particularly docosahexaenoic acid(22:6n-3,DHA),play crucial roles in the reproductive health of vertebrates,including humans.Nevertheless,the underlying mechanism related to this phenomenon remains largely unknown.In this study,we employed two zebrafish genetic models,i.e.,elovl2^(-/-)mutant as an endogenous DHAdeficient model and fat1(omega-3 desaturase encoding gene)transgenic zebrafish as an endogenous DHA-rich model,to investigate the effects of DHA on oocyte maturation and quality.Results show that the elovl2^(-/-)mutants had much lower fecundity and poorer oocyte quality than the wild-type controls,while the fat1 zebrafish had higher fecundity and better oocyte quality than wildtype controls.DHA deficiency in elovl2^(-/-)embryos led to defects in egg activation,poor microtubule stability,and reduced pregnenolone levels.Further study revealed that DHA promoted pregnenolone synthesis by enhancing transcription of cyp11a1,which encodes the cholesterol side-chain cleavage enzyme,thereby stabilizing microtubule assembly during oogenesis.In turn,the hypothalamic-pituitary-gonadal axis was enhanced by DHA.In conclusion,using two unique genetic models,our findings demonstrate that endogenously synthesized DHA promotes oocyte maturation and quality by promoting pregnenolone production via transcriptional regulation of cyp11a1.
Yi LiXuehui LiDing YeRu ZhangChengjie LiuMudan HeHoupeng WangWei HuYonghua Sun
Aluminum(Al)can lead to an exposure of creature in varieties ways for its universality,and it could disturb normal physiological metabolism,with the damage to multisystem including reproduction.Since the oocyte quality is critical for female reproduction,we inspected the toxicity of Al on mouse oocyte maturation.We constructed in vitro exposure mouse model,and we found that 5 mmol/L Al had adverse effects on oocyte maturation by impairing organelle and cytoskeleton.Aberrant spindle and misaligned chromosomes which might be considered to be caused by elevated levels of acetylation,as well as abnormal distribution of actin dynamics could hinder normal meiosis of oocytes.Organelle dysfunction indicated that Al affected proteins synthesis,transport and digestion,which would further damage oocyte maturation.In order to explore the mechanism of Al toxicity,our further investigation demonstrated that Al caused mitochondrial dysfunction and imbalance calcium homeostasis,resulting in limited energy supply.Moreover,high level of reactive oxygen species,DNA damage and apoptosis caused by oxidative stress were also the manifestation of Al toxicity on oocytes.In conclusion,our study provided the evidence that Al exposure affected oocyte quality through its effects on spindle organization,actin dynamics,organelle function and the induction of DNA damage-related apoptosis with mouse model.
Hongge LiJingcai LiuWeihua NongMengying ShenSheng DouShaochen SunJunli Wang
