A key objective of the dairy industry is to balance genetic progress with reproductive efficiency. Ovum pick-up followed by in vitro embryo production (OPU-IVP) is a pivotal technology for accelerating genetic gain. However, the relationship between follicle size and oocyte developmental competence in high-producing dairy cows under hormonal stimulation remains to be fully elucidated. This study systematically evaluated the effects of follicle diameter ovum pick-up on OPU-IVP outcomes and the underlying follicular fluid (FF) microenvironment. A total of 109 high-yielding Holstein cows were subjected to ovarian stimulation and OPU. Follicles were categorized as small (2.0–5.9 mm), medium (6.0–9.9 mm), or large (10.0–20.0 mm). Oocyte recovery, quality, and developmental competence were assessed. FF was analyzed for hormonal profiles, including anti-Müllerian hormone (AMH), estradiol (E2), follicle-stimulating hormone (FSH), and progesterone (PROG); oxidative stress markers, including malondialdehyde (MDA), glutathione peroxidase (GPx), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC); and untargeted metabolomics (n = 10 per group). Consistently, oocytes from medium follicles exhibited superior developmental competence, achieving the highest maturation (89.93%), cleavage (72.19%), and blastocyst rates (41.88%). In contrast, large follicles had a low recovery rate (32.64%), a high proportion of degenerated oocytes (32.00%), and reduced embryonic efficiency. Metabolomic profiling revealed distinct microenvironmental differences, with medium follicles enriched in pathways like pyruvate metabolism and arachidonic acid metabolism indicating an optimal metabolic state. Hormonally, AMH decreased while E2 and PROG increased with follicle size. Large follicles exhibited significantly elevated MDA levels, indicating oxidative stress, without a concurrent rise in antioxidant capacity. In conclusion, while small follicles provide an abundant source of morphologically good oocytes, medium follicles (6.0–9.9 mm) represent a distinct “window of competence” for OPU-IVP, characterized by a follicular microenvironment most conducive to embryo production. Excessive reliance on large follicle aspiration should be avoided due to signs of over-maturity and oxidative damage. These findings provide a physiological basis for optimizing OPU strategies to enhance IVP efficiency in high-producing dairy cows.

Assessment of Glycoprotein Hormones Level (Inhibin and Activin) in the Follicular Fluid at The Time of Ovum Pickup During ICSI and Its Impaction on the Success Rate of ICSI

Lipopolysaccharide reduces progesterone and cytokines in equine follicular fluid without affecting oocyte development in vitro.

Differential associations of PFAS in follicular fluid and serum with reproductive hormones: Insights from a Chinese IVF cohort GIVES.

Ovulation-derived extracellular vesicles exhibit sustained oncogenic influence on the exposed fallopian tube fimbrial cells after drainage into peritoneal cavity.

Luteinizing hormone (LH) plays a crucial role in follicle development, ovulation induction, and the regulation of key reproductive events. However, the efficacy of LH within the follicular microenvironment largely depends on the capacity of follicular cells to express its receptor. This study aims to investigate whether granulosa cells (GCs) can acquire LHR through extracellular vesicles (sEVs) present in follicular fluid (FF) from follicles of varying sizes. In the first experiment, GCs and sEVs were collected from the FF of small (3–5 mm), medium (5.1–7 mm), and large (7.1–9 mm) ovarian follicles from Bos taurus indicus cows. In the second experiment, GCs and sEVs were collected from the FF of small (3–6 mm) and large (8–14 mm) follicles from Bos taurus taurus cows. Initially, we assessed the ability of sEVs to carry LHR mRNA by comparing its expression profiles in sEVs derived from different size follicles. Our findings revealed that as follicular development progresses, LHR levels in FF sEVs decrease, while in corresponding GCs, from which the sEVs primarily originate, show increased LHR expression. To further investigate whether GCs represent an additional source of FF sEVs carrying LHR mRNA, GC cultures were established and sEVs secreted into the culture medium (ME-sEVs) were analyzed for LHR mRNA levels. A similar pattern was observed in ME-sEVs derived from GCs of small versus large follicles, with decreased LHR mRNA levels in sEVs secreted by GCs from large follicles compared to small follicles. This suggests that LHR is likely packaged into sEVs in small follicles stage, and shuttled into follicular cells during follicular growth, preparing them for the ovulatory stimulus. Our study uncovers a possible mechanism of LHR acquisition by GCs, which involves EVs and can possibly be involved in follicle quality and ability to respond to LH stimulus.

Extracellular vesicles from the follicular fluid of competent oocytes improve blastocyst yields when supplemented during simulated physiological oocyte maturation in cattle.

Associations of urinary N, N-dimethylformamide metabolite concentrations with ovarian reserve and in vitro fertilization outcomes based on a prospective cohort study in China.

Environmental endocrine disrupting chemicals in urine and follicular fluid: Association with steroid hormones and risk of polycystic ovarian syndrome

Impaired metabolic cooperation between oocyte and granulosa cells may contribute to the disrupted folliculogenesis and poor oocyte quality in PCOS.

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

Oxidative stress and redox homeostasis play crucial roles in ovarian function, influencing oocyte quality and developmental competence. This study evaluated the population-level associations between thiol-disulphide homeostasis, oxidative stress biomarkers, antioxidant enzyme activity, and oocyte quantity and quality in cattle. Blood and follicular fluid samples were analysed from cattle to assess total thiol (TTL), native thiol (NTL), disulphide (DS), nitric oxide (NO), superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) levels. Oocytes were collected and classified based on morphological characteristics. Statistical analyses revealed a positive correlation between TTL and total oocyte count (TOC), suggesting that higher thiol availability enhances oocyte production. Conversely, elevated NTL levels were negatively associated with oocyte quality, indicating that an imbalance in thiol-disulphide homeostasis may impair follicular development. GPX activity exhibited a significant negative association with both TOC and high-quality oocyte count (HQOC), suggesting that excessive antioxidant activity might disrupt essential redox signalling pathways required for oocyte maturation. However, SOD, CAT and NO levels were not significantly correlated with oocyte count or quality, indicating a complex interplay between oxidative stress markers and reproductive efficiency. These findings demonstrate significant associations between thiol-disulphide balance, GPX activity, and both total and HQOCs, highlighting the relevance of redox status in follicular physiology. Further research is needed to explore targeted antioxidant interventions to optimise reproductive outcomes in livestock. Understanding the role of oxidative balance in oocyte maturation may contribute to improving assisted reproductive technologies (ART) such as invitro fertilisation (IVF) and embryo transfer in cattle.

Ovarian aging reduces oocyte quality and is a major limiting factor in assisted reproductive technologies (ART) such as IVF and ICSI. This review highlights the role of follicular fluid (FF) as a mirror of the oocyte microenvironment and summarizes molecular alterations linked to aging and ovarian dysfunction. We focus on metabolites, proteins, microRNAs, and exosomes within FF that influence oocyte quality and reproductive outcomes, aiming to identify novel clinical biomarkers. Follicular fluid contains diverse biomolecules-including hormones, growth factors, cytokines, oxidative stress markers, and exosomes-that shape oocyte maturation, fertilization capacity, and embryonic competence. Recent multi-omics studies suggest that metabolic and redox-related molecules, amino acid and lipid profiles, and exosomal microRNAs are associated with ART outcomes. Mitochondrial DNA (mtDNA) and cell-free mtDNA (cf-mtDNA) also emerge as promising indicators of mitochondrial function and oocyte developmental potential. However, variations in patient background, sample handling, and analytical methods limit reproducibility. Overall, FF provides a valuable, minimally invasive source for assessing the oocyte environment and understanding ovarian aging. Future studies should integrate metabolomic, proteomic, transcriptomic, and exosomal data through multi-omics and functional analyses to establish reliable clinical biomarkers. Such advances may enable precise assessment of oocyte quality, prediction of ART success, and early diagnosis of ovarian aging.

Comparison of the metabolome of follicular fluid in GnRH agonist versus antagonist protocols during in vitro fertilization cycles.

Associations between concentrations of microplastics in follicular fluid and the risk of diminished ovarian reserve.

Background. Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder affecting 15–20% of women of reproductive age. It is characterized by hyperandrogenism, anovulation, insulin resistance and chronic low-grade inflammation, contributing to metabolic and reproductive dysfunction. Vitamin D deficiency is highly prevalent in PCOS, affecting up to 85% of patients, and is increasingly recognized as a factor influencing hormonal balance, glucose metabolism and fertility. Due to the presence of vitamin D receptors in ovarian, endometrial and metabolic tissues, vitamin D may play a role in steroidogenesis, follicular development, endometrial receptivity and insulin sensitivity. Emerging evidence suggests that vitamin D status may affect menstrual regularity and outcomes of assisted reproductive techniques, including in vitro fertilization (IVF). Aim. To assess the relationship between vitamin D status, metabolic and hormonal parameters, and fertility outcomes in women with PCOS. Material and methods. A narrative review of the literature was conducted using the PubMed database. Studies were identified using keywords related to PCOS, vitamin D, fertility, insulin resistance and IVF. Clinical trials, observational studies and experimental research were included. This study was conducted as a narrative literature review and did not involve original patient data. Results. Vitamin D supplementation was associated with improvements in insulin resistance, lipid metabolism and inflammatory markers, as well as reductions in androgen levels. Higher serum and follicular fluid vitamin D concentrations were linked to improved ovarian response, oocyte quality and IVF outcomes, although findings regarding ovulation and pregnancy rates remain inconsistent.

Oocyte-granulosa cell complexes (OGCs) cultivation is crucial for advancing reproductive biotechnology but remains incomplete and needs further optimization. Insulin-like growth factor-I (IGF-I) regulates granulosa cell proliferation and apoptosis, and numerous studies have confirmed its role in promoting ovarian follicle development. Porcine follicular fluid (PFF) contains factors beneficial for oocyte growth, which may enhance oocyte development. To investigate whether IGF-I and PFF improve the in vitro culture efficiency of porcine OGCs, we cultured OGCs with IGF-I (0, 10, 50, 100 ng/mL) and PFF (from 3 to 6 mm follicles) at concentrations of 0, 2.5%, 5%, 10%, respectively. The results revealed that 50 and 100 ng/mL IGF-I significantly increased the antrum formation rate of OGCs (from 61.11 ± 7.35% to 88.89 ± 7.35%) and diameter growth of oocytes (from 108.77 ± 0.27 µm to 114.94 ± 0.58 and 113.29 ± 0.50 µm, respectively). However, only the 50 ng/mL group, but not the 100 ng/mL group, significantly improved the maturation rate (38.13 ± 3.77% vs. 25.00 ± 3.27%, p < 0.05) of oocytes. Additionally, 50 ng/mL IGF-I downregulated BAX (a pro-apoptotic gene) and upregulated BCL-2 (an anti-apoptotic factor) in granulosa cells, ultimately reducing apoptosis. In contrast, none of the PFF doses used in this study induced the formation of enclosed antrum-like structures in OGCs, nor did they significantly enhance their in vitro development. Our findings demonstrate that 50 ng/mL IGF-I effectively promotes the in vitro growth of porcine early antral follicle-derived OGCs by reducing apoptosis, whereas tested PFF concentrations had no beneficial effects and induced abnormal granulosa cell growth. How PFF modulates the adherent and spreading growth of granulosa cells has not been fully elucidated and requires further clarification.

First detection of Leptospira spp. in cumulus-oocyte complexes from naturally infected cows.

NAD+ rescues Phosphatidylinositol-induced granulosa cell Pyroptosis to restore follicular development in PCOS.

Sperm Selection through Microvesicle-Mediated ChemotaxisInduced by Follicular Fluid and Cumulus Cells.