A transcriptomic map of ligand-receptor interactions within bovine antral follicles predicts intrafollicular factors for improving oocyte quality

The Effect of the Oocyte Microenvironment on Its Maturation

It is demonstrated how fundamental knowledge of the oocyte microenvironment can be harnessed to design cellular technologies for clinical applications and enhances the efficacy of assisted reproductive technologies (ART).

Unveiling the formation of the primordial follicle pool in goats: Insights from single-cell omics analysis.

This study provides the first single-cell transcriptomic atlas of goat ovarian development, delineating dynamic gene expression patterns and cellular interactions during primordial follicle pool establishment, and advance understanding of conserved and species-specific mechanisms governing female reproductive lifespan in mammals.

Perifollicular stromal cells sustain folliculogenesis via MDK–NCL signaling in mice and humans

The unique spatial confinement and regulatory capacity of perifollicular SCs endow them with the potential to become important components of the follicular functional unit, providing new theoretical support for understanding the molecular regulatory mechanisms of ovarian aging from the perspective of the follicular microenvironment.

Integrated molecular analysis of granulosa cells and follicular fluid extracellular vesicles reveals predictive biomarkers of oocyte maturation in the southern white rhinoceros

Introduction Assisted reproductive technologies (ARTs) are an imperative conservation tool to rescue species from extinction. An essential step towards technological advancements and ARTs’ successes is identifying optimal in vitro culture conditions to mature oocytes, carry out fertilization, and culture embryos for future transfer. The role of follicular fluid-derived extracellular vesicles (FF-EVs) and granulosa cells (GC) in follicular development, oocyte maturation, and fertilization has been extensively studied for decades in human and domestic species models. Methods This study aimed to identify transcriptomic differences in GC mRNA and miRNA expression, as well as miRNA cargo in FF-EVs in the southern white rhinoceros (SWR), and to integrate these datasets to uncover coordinated regulatory networks associated with oocytes that matured (with polarbody, PB) compared to those that failed to mature (without polar body, NoPB) following in vitro maturation. Results Overall, in GCs, 1,117 transcripts (including both annotated and unannotated) were differentially expressed between groups. In GC-derived miRNAs, 11 were differentially expressed, all of which were upregulated in the PB group. In FF- EV samples, 15 miRNAs were identified as differentially expressed between the two groups. Comparison of predicted miRNA targets with the differentially expressed genes revealed multiple overlapping genes, suggesting a coordinated post-transcriptional regulation mechanism. Discussion These miRNA-mRNA interactions are potential targets for further investigation, both as potential modulators to improve in vitro maturation outcomes and as biomarkers for predicting oocyte maturation potential in the SWR. In conclusion, the EV–mediated mRNA-miRNA signaling occurring during folliculogenesis in the SWR may offer critical insights into physiological reproductive conditions that contribute to oocyte maturation, ultimately informing the development of novel reproductive strategies to enhance ART outcomes in this species and others.

DHX36 regulates antral follicle development and ovulation as a non-OSF maternal factor by maintaining oocyte homeostasis and supporting OSF delivery

Intrafollicular Hormonal Environment of Equine Follicles Aspirated for In Vitro Embryo Production.

BACKGROUND During transvaginal oocyte aspiration (TVA), follicle selection is based primarily on ultrasonographic diameter, although follicles of similar size may differ in their physiological and endocrine status. AIMS This study aimed to characterize the intrafollicular endocrine environment of equine follicles at aspiration and evaluate associations with oocyte developmental outcomes. METHODS Follicular fluid was collected from antral follicles ranging from 5 to 40 mm in diameter prior to routine oocyte aspiration, and concentrations of luteinizing hormone (LH), anti-Müllerian hormone (AMH), and inhibins were quantified. Recovered cumulus-oocyte complexes were subjected to in vitro maturation, intracytoplasmic sperm injection, and embryo culture to assess maturation and blastocyst development. RESULTS AMH concentrations were highest in 15 mm follicles and declined in larger follicles. Inhibin B was positively correlated with AMH, indicating coordinated granulosa cell endocrine activity. Inhibin A concentrations were significantly higher in follicles from which oocytes were not recovered. No consistent associations were detected between follicular fluid hormone concentrations and oocyte maturation, and blastocyst formation could not be robustly evaluated because of the limited number of embryos produced. Substantial variation in hormone concentrations was observed, particularly within the 10-25 mm range, which is commonly aspirated during TVA. CONCLUSION These findings indicate that intrafollicular AMH and inhibins primarily reflect granulosa cell endocrine status, and their role as predictors of oocyte competence remains to be determined in future studies. The marked endocrine variability among follicles of similar diameter suggests that follicle size alone does not reliably represent functional follicular stage in the mare.