Search Results (293)

Oxidative stress is a fundamental mechanism that impacts reproductive function by altering gamete quality, fertilisation, and the initial development of embryos. Excessive reactive oxygen species lead to the oxidation of polyunsaturated fatty acids in the cell membranes of sperm, oocytes, and adjacent somatic cells. F2-isoprostanes and isofurans are two of the most dependable indicators of oxidative lipid damage among the byproducts generated during free radical-mediated lipid oxidation. Both arise from the non-enzymatic peroxidation of arachidonic acid and provide a chemically stable depiction of in vivo oxidative processes. Reproductive studies indicate that elevated levels of F2-isoprostanes are associated with diminished sperm motility, compromised membrane stability, and an increased risk of DNA fragmentation in various forms of male infertility. Lipid peroxidation products have been detected in follicular fluid inside the female reproductive system, suggesting a relationship between oxidative imbalance, granulosa cell metabolism, and oocyte competency. Isofurans, which are more prevalent in the presence of elevated oxygen levels, may indicate oxidative stress in mitochondria and complications with cellular respiration. The current comprehension of lipid peroxidation indicators in infertility and assisted reproduction remains insufficient. This review aims to synthesise current information on isoprostanes and isofurans as reliable indicators of oxidative lipid damage in reproductive biology, highlighting their effects on gamete quality, mitochondrial dysfunction, and results in assisted reproduction. Our research seeks to clarify the biological importance of current experimental and clinical findings, highlighting their potential as clinically relevant biomarkers in reproductive medicine. Full article

Background and Objectives: Endometriosis is a multifactorial gynecological condition associated with impaired fertility; however, its impact on embryo competence remains incompletely understood. This study aimed to evaluate embryo competence through a stepwise analysis of IVF outcomes across the developmental continuum, while also comparing patients with endometriosis and controls. Materials and Methods: A retrospective observational study was conducted, including 160 patients undergoing IVF, comprising 55 patients with endometriosis and 105 controls. Clinical and embryological data were analyzed sequentially across key developmental stages, including oocyte retrieval, metaphase II (MII) oocyte formation, fertilization (2PN), embryo development, and euploidy in a subgroup undergoing preimplantation genetic testing for aneuploidy (PGT-A). Stage-specific efficiency rates were calculated, and correlations between early- and late-developmental parameters were assessed. In addition, comparative analysis between groups was performed. Results: A progressive decline in developmental efficiency was observed across the IVF continuum, with approximately one-quarter of retrieved oocytes reaching the embryo stage and only a small proportion ultimately resulting in euploid Blastocysts. Strong positive correlations were identified among early-stage parameters, particularly retrieved oocytes, MII oocytes, and embryo yield (r = 0.77–0.96, p < 0.001), indicating that ovarian response and oocyte maturity significantly influence downstream outcomes. However, efficiency-based parameters showed limited predictive value for chromosomal competence. A moderate association was observed between MII oocytes and euploid Blastocysts (r = 0.58), whereas the relationship between embryo number and euploidy remained weak. Comparative analysis revealed no statistically significant differences between the endometriosis and control groups across the evaluated embryological parameters (p > 0.05 for all comparisons), suggesting that sequential analyses may provide complementary insight beyond direct comparisons. Conclusions: IVF outcomes follow a sequential developmental trajectory with a progressive decline in efficiency across stages. In endometriosis, early developmental competence appears to be affected, while chromosomal competence remains relatively preserved. Full article

Oocyte maturation is a pivotal event in teleost reproduction that directly determines egg quality, fertilization success, and the developmental competence of early embryos. However, the transcriptional and post-transcriptional regulatory mechanisms operating within oocytes during maturation in marine teleosts remain poorly understood. In the present study, the orange-spotted grouper (Epinephelus coioides), an economically important marine aquaculture species, was used as a model. Oocytes at four distinct maturation stages were obtained by microscopically removing the surrounding follicular layers, followed by integrated mRNA-seq and miRNA-seq analyses to characterize the molecular regulatory landscape underlying oocyte maturation and hydration. The results showed that, as maturation progressed, oocyte diameter and wet weight increased significantly, accompanied by a marked decrease in Na⁺ content, a significant increase in K⁺ content, and the continuous accumulation of most free amino acids, indicating the gradual establishment of an osmotic basis favorable for oocyte hydration. Transcriptomic analysis further revealed extensive transcriptional remodeling during both the early and late phases of maturation. Differentially expressed genes were significantly enriched in pathways related to oocyte meiosis, cytokine signaling, lipid metabolism, DNA replication, cell cycle regulation, ribosome biogenesis, spliceosome function, oxidative phosphorylation, and mitochondrial activity, suggesting that oocyte maturation is a dynamic process characterized by a shift from basal growth maintenance to metabolic reprogramming, maternal transcript remodeling, and terminal maturation responses. miRNA profiling identified a large number of stage-specific differentially expressed miRNAs, including let-7d-5p, miR-22a-3p, and novel-miR-20/27/118, whose predicted target genes were mainly enriched in ribosome-related pathways, oxidative phosphorylation, DNA replication, transcriptional regulation, and signal transduction. Moreover, the miRNA–TF–mRNA regulatory network demonstrated that miRNAs may not only directly repress target genes, but also mediate hierarchical regulatory cascades through transcription factors, thereby coordinately participating in cell cycle progression, cytoskeletal remodeling, vesicular transport, and immune- and cell communication-related responses. Collectively, this study provides the first systematic temporal atlas of mRNA and miRNA regulation during oocyte maturation and hydration at the oocyte level in a marine teleost, thereby deepening our understanding of the molecular basis of meiotic resumption and egg quality formation, and offering valuable theoretical support for the optimization of artificial breeding and the identification of key molecular targets in grouper reproduction. Full article

Infertility is a global health problem, with male factors contributing to nearly half of all cases. Up to 30% of male infertility is classified as idiopathic, in part because routine semen analysis does not assess sperm fertilizing competence. Capacitation is a complex process that endows spermatozoa with the competence to fertilize the oocyte, and it depends on oxidant-driven phosphorylation events. These events include increased PKA substrate and tyrosine phosphorylation, which promote hyperactivated motility and the acrosome reaction. These pathways are normally restrained by decapacitation factors that must be relieved in the female reproductive tract before capacitation can proceed. Protein CoAlation is an antioxidant modification of protein thiols through a disulfide bond with coenzyme A (CoASH). We previously detected protein CoAlation in human spermatozoa and observed that its levels decline during capacitation, but its function was unknown. We hypothesized that protein CoAlation functions as a decapacitation mechanism that prevents redox signalling, enabling oxidative activation of phosphorylation events during capacitation. Using spermatozoa from healthy human donors, we leveraged subcellular fractionation, immunocytochemistry, computer-assisted sperm analysis (CASA), and immunoblotting to determine the sperm protein CoAlation profile, assess CoASH biosynthetic enzymes, and test how pharmacological modulation of CoAlation levels influences capacitation. CoAlated proteins were distributed across intracellular sperm compartments, and spermatozoa possess the CoASH biosynthetic enzymes PANK2 and CoASY, indicating an intrinsic capacity for CoAlation. Inhibition of CoASH biosynthesis reduced CoAlation and enhanced PKA substrate phosphorylation, tyrosine phosphorylation, hyperactivated motility, and the progesterone-induced acrosome reaction under capacitating conditions. Pantothenic acid supplementation increased CoAlation and suppressed these processes without impairing viability or baseline motility. These findings indicate that high levels of protein CoAlation in several protein bands are a pre-existing feature of the non-capacitated state that restrains the redox-regulated events of capacitation and that its decline is required to permit sperm capacitation. CoAlation levels may emerge as a biomarker of sperm capacitation and fertilizing competence. Full article

Nerve Growth Factor (NGF), a member of the neurotrophin family, is currently regarded as a key regulator of ovarian physiology beyond its well-known neurotrophic functions. The mammalian ovary is one of the most highly innervated peripheral organs. Increasing evidence indicates that NGF and its receptors, TrkA and p75NTR, are widely expressed in ovarian tissues. Through the activation of the PI3K/AKT, MAPK/ERK, and PLCγ signaling pathways, NGF influences granulosa cell proliferation, steroidogenesis, and ovulation. Physiological levels of NGF are essential for primordial follicle activation, FSH receptor expression, and effective bidirectional communication between oocytes and surrounding somatic cells. As a result, NGF also regulates oocyte maturation and developmental competence. The disruption of NGF signaling can lead to serious health issues. Both low and high levels of NGF negatively affect folliculogenesis and fertility. Elevated intraovarian NGF results in sympathetic over-innervation, altered steroid production, and polycystic ovarian features. In addition, increased NGF expression has been linked to endometriosis and ovarian cancer progression. Clinical studies further suggest that follicular NGF levels may serve as indicators of ovarian reserve and reproductive outcomes in assisted reproduction. This narrative review synthesizes the current knowledge on NGF roles in ovarian physiology and disease. It highlights NGF’ dual functions as a central regulator of follicular dynamics, and as a potential biomarker and therapeutic target for common reproductive system diseases. Full article

With the continuous advancement in reproductive biology, oocyte vitrification has become a critical technology for preserving female germplasm and protecting it from environmental disruptions. This technique also eliminates temporal and spatial constraints in animal embryo engineering research. However, during the vitrification of animal oocytes, exposure to low temperatures and high concentrations of cryoprotectants can cause various forms of damage, including cytoskeletal disruption, spindle abnormalities, mitochondrial dysfunction, apoptosis, oxidative stress and epigenetic modifications. These issues are now understood to severely restrict the subsequent developmental competence of oocytes, resulting in lower cleavage and blastocyst formation rates than those of fresh oocytes. Currently, the mechanisms of cryodamage in vitrified oocytes remain poorly understood, and standardized strategies to enhance vitrification efficiency have yet to be firmly established. This review provides a formal overview of the physiological factors underlying oocyte sensitivity to vitrification, alongside the mechanisms of cryodamage and the variables influencing post-thaw survival and reproductive success. It evaluates strategies for mitigating vitrification-induced stress, compares interspecies differences, and addresses current research limitations. By identifying future directions, this review offers new insights for optimizing mammalian oocyte cryopreservation techniques. Full article

Background/Objectives: Women undergoing fertility preservation by oocyte vitrification before oncological treatments often have a poorer ovarian response to stimulation than healthy women. This indicates that cancer itself can adversely affect ovarian function. However, this impact remains unclear, and its underlying mechanisms are poorly understood. We investigated in this study whether breast cancer, the most common form of cancer in women of reproductive age, alters ovarian function by itself. Methods: For this purpose, we compared the ovarian response to hormonal stimulation in women with breast cancer undergoing oocyte cryopreservation with that in oocyte donors, adjusting for age and BMI. We analysed our data according to the molecular subtype of breast cancer, tumour grade, lymph node invasion, and BRCA1 mutation status. Secondly, we evaluated whether breast cancer alters cholesterol homeostasis in cumulus cells, given its essential role in oocyte quality. The expression of genes involved in cholesterol biosynthesis was analysed in cumulus cells using RT-qPCR, while the concentrations of cholesterol and its intermediates were quantified in follicular fluid using GC-FID and GC-MS/SIM. Results: Compared with oocyte donors, breast cancer patients exhibited a significant decrease in collected oocytes after stimulation. At the molecular level, our data revealed a significant deregulation of cholesterol biosynthesis gene expression in cumulus cells of women with breast cancer. The quantification of cholesterol and its intermediates in follicular fluid revealed altered concentrations in women with breast cancer, suggesting a disrupted follicular microenvironment. Conclusions: These findings suggest that breast cancer impairs ovarian function, at least in part, by disrupting cholesterol homeostasis, which can lead to reduced oocyte competence. Full article

Embryos being treated using assisted reproductive technology (ART) are unavoidably exposed to physical stressors, thus producing reactive oxygen species (ROS) which trigger mitophagy to support embryonic development. However, the mechanisms underlying the regulation of mitophagy in early embryonic development remain largely unexplored. Here, we found that Mucin 1 (MUC1) exhibited a uniform distribution in both mouse and human oocytes, and its expression peaked at the blastocyst stage. Further analysis revealed that Muc1 knockout impairs blastocyst formation in vitro. Correspondingly, Muc1 knockout led to the accumulation of mitochondrial reactive oxygen species (mtROS) and a reduction in phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1)/Parkinson protein 2 (PARK2/Parkin)-dependent mitophagy. Stimulation of mitophagy via low-dose carbonyl cyanide 3-chlorophenylhydrazone (CCCP) treatment rescued the blastocyst formation defect in Muc1-null embryos. Vitamin C supplementation effectively scavenged mtROS and restored developmental competence. Together, our findings establish that MUC1 safeguards early embryonic development by promoting mitophagy to decrease mtROS levels in vitro. Moreover, vitamin C could compensate for Muc1 deficiency by eliminating mtROS. This study not only identified a new function of MUC1 in protecting early embryonic development in vitro, but also revealed a novel mechanism of mitophagy regulation in early embryos, which has potential applications for ART. Full article

Age-related decline in oocyte quality is closely associated with mitochondrial dysfunction and oxidative imbalance, which disrupt redox-sensitive meiotic signaling and compromise embryo developmental competence. Rescue in vitro maturation (r-IVM) enables the utilization of immature oocytes retrieved during conventional in vitro fertilization (IVF) cycles. However, the developmental potential of r-IVM oocytes remains limited, particularly in women of advanced maternal age. This study evaluated whether transient caffeine supplementation during r-IVM improves the developmental competence of immature human oocytes in clinical assisted reproduction technology cycles. Immature oocytes obtained during conventional IVF were cultured with or without short-term caffeine exposure during r-IVM prior to standard culture conditions. After maturation, metaphase II oocytes underwent intracytoplasmic sperm injection, and embryonic development was assessed by fertilization rate, day 3 good-quality embryo formation, and blastocyst development. Although caffeine supplementation did not significantly affect nuclear maturation rates, it significantly increased fertilization efficiency and the proportion of good-quality embryos compared with controls. These effects were most pronounced in women aged ≥37 years. Time-lapse morphokinetic analysis further revealed more synchronized developmental kinetics in embryos derived from caffeine-treated oocytes, resembling those derived from in vivo-matured oocytes. Collectively, these findings suggest that transient caffeine exposure during r-IVM enhances post-fertilization developmental competence. The underlying mechanisms remain to be elucidated, and future studies are required to determine whether redox-sensitive meiotic pathways and mitochondrial function are involved. Full article

Increased heat levels can affect follicle development, oocyte maturation, and bovine fertility by disrupting amino acid (AA) metabolism and oocyte competence. This study aimed to explore the effect of heat shock on AA metabolism in bovine cumulus cells (CCs) or denuded oocytes (DOs). CCs and DOs were separately cultured for 24 h in vitro at 38.5 °C (control group), 39.5 °C (moderate heat shock-CC, MHS-CC group), or 40.5 °C (high heat shock-CC, HHS-CC group). AA levels were analyzed in 24-h in vitro maturation media using high-performance liquid chromatography. The findings indicated that the HHS-CC group consumed more AAs than the control (p = 0.04) or MHS-CC group (p = 0.03). Compared with the control and HHS-CC groups, the MHS-CC group exhibited elevated alanine levels (p = 0.02). The MHS-CC (p = 0.03) and HHS-CC (p = 0.03) groups exhibited significantly greater glutamine depletion than the control group. The HHS-DO group exhibited significant lysine depletion (p < 0.01) but produced more tryptophan than the control and MHS-DO groups (p = 0.02). In contrast to the control and MHS-DO groups, the HHS-DO group displayed a notably elevated level of appearance (p = 0.005) and net balance (p = 0.005) for all AAs. The findings imply that heat shock may alter the metabolism of certain AAs in CCs and DOs, thereby affecting the developmental competence of bovine oocytes. Full article

Novel brominated flame retardants (NBFRs), including 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), are emerging endocrine-disrupting chemicals, though their direct effects on female gamete maturation remain insufficiently characterized. In this study, we used a refined zebrafish oocyte in vitro maturation (IVM) model integrating germinal vesicle breakdown (GVBD) assessment with real-time, image-based oocyte diameter quantification. The workflow incorporated donor-condition optimization and diameter-based quality control during sorting. Oocytes from donors 4 to 5 months post-fertilization (mpf) showed more consistent diameter dynamics at the dish level than those from donors 3 to 4 mpf. Mixed-sex co-housing was associated with higher GVBD and larger Δdiameter than separated housing, although this comparison should be considered preliminary. Under DHP induction, BTBPE (1–1000 nM) consistently suppressed GVBD and attenuated maturation-associated diameter increases, with a non-monotonic-like response pattern. These findings indicate that BTBPE impairs oocyte maturation competence in vitro and supports real-time morphometric tracking as a practical QC component for zebrafish IVM workflows. Full article

Non-invasive assessment of oocyte quality remains a challenge in assisted reproductive technology (ART). Through their bidirectional communication with the gamete, cumulus cells (CCs) act as a functional mirror of oocyte competence; however, the specific angiogenic signature within this microenvironment is still poorly understood. In the present study, we performed RNA-seq on CCs from healthy oocyte donors and infertile patients, utilizing a multi-pipeline bioinformatic approach (STAR-Cufflinks, TopHat-HTSeq, and HISAT2-StringTie) to establish a high-confidence, exploratory transcriptomic profile. A set of 234 differentially expressed genes (DEGs) consistently identified across pipelines was obtained, with functional enrichment highlighting blood vessel morphogenesis and angiogenesis as primary drivers of transcriptomic divergence between groups. RT-qPCR validation in individual samples confirmed statistically significant differences for ANKRD22 (upregulated) and E2F7 (downregulated) in infertile patients, while other angiogenesis-related genes, including ANGPT1, ANGPT2 and THBS1, showed consistent but non-significant expression trends, suggesting alterations in angiogenesis-related processes within the follicular microenvironment. These findings support the presence of coordinated angiogenesis-related alterations in cumulus cells and provide a basis for future studies exploring their potential relevance in oocyte competence and ART outcomes. Full article

Oocyte competency is a crucial determinant of fertilisation success and the initial development of embryos in assisted reproductive technologies. The metabolic and biochemical environment of the ovarian follicle is crucial for determining oocyte developmental potential, alongside genetic integrity. The follicular microenvironment includes a complex network of signalling chemicals that regulate mitochondrial activity, steroidogenesis, oxidative balance, and cellular energy metabolism. Recently, metabolic hormones originating from adipose tissue and skeletal muscle, namely, adipokines and myokines, have received considerable focus as crucial regulators of ovarian physiology. Adiponectin, irisin, and the recently identified hormone asprosin have emerged as crucial metabolic regulators influencing granulosa cell activity, mitochondrial bioenergetics, insulin signalling pathways, and redox homeostasis inside the follicular niche. Adiponectin mostly provides metabolic protection by activating AMP-activated protein kinase (AMPK) and improving insulin sensitivity, which in turn enhances mitochondrial efficiency and steroidogenic function in granulosa cells. Irisin, derived from the breakdown of fibronectin type III domain-containing protein 5 (FNDC5), aids the developing oocyte by facilitating mitochondrial biogenesis, augmenting oxidative phosphorylation, and altering cellular defence mechanisms against oxidative stress. Conversely, asprosin has been associated with glucogenic signalling, metabolic stress, and probable mitochondrial malfunction, suggesting a possible relationship between systemic metabolic problems and negative reproductive consequences. Clinical and experimental research indicate that the levels of these metabolic regulators in follicular fluid may correlate with ovarian response, oocyte quality, fertilisation rates, and embryo development during in vitro fertilisation cycles. This review consolidates current molecular, cellular, and clinical information, clarifying the pathways by which adipokines and myokines influence follicular metabolism and impact oocyte competency. Understanding the metabolic connections between systemic endocrine signals and the follicular milieu may provide novel indicators for reproductive prognosis and provide new treatment targets to improve assisted reproduction outcomes. Full article

Reproductive aging is characterized by progressive decline in ovarian reserve, reduced oocyte competence, and impaired endocrine coordination. Although these phenotypic changes are well documented, the molecular mechanisms that integrate aging-associated stress signals into coordinated ovarian dysfunction remain incompletely understood. Increasing evidence indicates that DNA methylation remodeling is closely associated with ovarian aging. Rather than representing isolated promoter-specific events, age-related methylation alterations may reflect progressive imbalance between DNA methyltransferases (DNMTs) and TET-mediated demethylation. Stress-responsive DNMT/TET dysregulation has been linked to distributed epigenetic remodeling across regulatory elements governing PI3K–AKT, TGF-β/SMAD, metabolic, and DNA damage response pathways in ovarian cell populations. We propose a network-level framework in which methylation drift preferentially affects highly connected regulatory hubs, potentially reducing transcriptional robustness and intercellular coordination within the follicular microenvironment. However, current human data remain largely correlative, and functional validation is required to determine whether methylation remodeling acts as a driver, amplifier, or biomarker of ovarian aging. Finally, we discuss translational implications, including circulating cell-free DNA signatures and epigenetic clock models, while emphasizing the importance of cell type-resolved and longitudinal studies. Collectively, the available evidence supports a model in which progressive DNMT/TET imbalance is associated with distributed pathway-level regulatory instability during ovarian aging. Full article

Bidirectional communication between the oocyte and surrounding follicular cells coordinates follicle growth, meiotic maturation, and the acquisition of competence. We aimed to identify genes related to follicular crosstalk and the secretory pathway as candidate mediators of cumulus–oocyte complex (COC) crosstalk in cattle. Expressed sequence tags (ESTs) from bovine COCs were retrieved from databases and screened for genes related to secretion and the secretory pathway using SignalP and SecretomeP, and transmembrane proteins were removed, yielding 13 candidate genes. Candidate expression was examined in two GEO RNA-seq datasets to assess enrichment in oocytes versus cumulus cells. RT–qPCR profiling across tissues and reproductive cell types enabled principal component analysis and correlation/network analysis, visualized as heatmaps and Cytoscape, revealing an INBHA-SERPINE2-SDF2L1 co-expression pattern. INHBA and SERPINE2 protein products are secreted, whereas SDF2L1 protein is a secretory pathway-associated, endoplasmic reticulum-resident chaperone. Promoter sequences of INHBA, SERPINE2, and SDF2L1 were scanned with FIMO using JASPAR motifs, identifying shared SMAD-associated motifs and FSH/cAMP-related motif families. The data support a co-regulation model in which endocrine FSH/cAMP and activin/TGF-β–SMAD inputs converge on a shared transcriptional program consistent with a putative INHBA–SERPINE2–SDF2L1 co-regulated module, linking cumulus extracellular matrix remodeling/protease control with oocyte ER protein folding capacity during COC maturation. Full article