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

Single-cell roadmap of bovine oogenesis and somatic niche interactions during fetal ovarian development

Integrated Single-cell Proteomic and Transcriptomic Landscape of Mouse Folliculogenesis.

Folliculogenesis is a complex process essential to female fertility, characterized by multifaceted communication between oocytes and granulosa cells (GCs). While transcriptional regulation during folliculogenesis has been extensively studied, the proteomic landscape remains largely unexplored. Here, we profiled both the proteomic and transcriptomic landscapes of single oocytes and their surrounding mini-bulk GCs across four consecutive stages, from secondary to preovulatory follicles. Integrated dual-omics analysis provided a high-resolution characterization of cell type-specific transcriptional and proteomic changes. Proteomic profiling revealed coordinated metabolic programs, in which oocytes shift toward lipid storage while GCs enhance energy production and steroidogenic metabolism to support oocyte maturation. These metabolic changes in oocytes were accompanied by dynamic remodeling of mitochondrial organization. In addition, we identified novel transcription factors involved in regulating folliculogenesis, as well as a SATB1-centered regulatory network that may reflect preparatory chromatin remodeling preceding zygotic genome activation. Furthermore, GDF9-BMPR2 signaling progressively increased from the secondary stage to the preovulatory stage, indicating strengthened intercellular communication between oocytes and GCs. Together, these findings provide mechanistic insights into oocyte development and follicle growth, with potential implications for novel fertility treatments and diagnostic strategies.

Identification of miR-187 as a regulator of early oogenesis and follicle growth in medaka ovary

MicroRNAs (miRNAs) are known regulators of ovarian function in vertebrates, yet their physiological roles in fish reproduction remain poorly understood. Here, we identified miR - 187 as one of the most ovarian-enriched miRNAs in medaka ( Oryzias latipes ) and we uncovered its function in vivo using CRISPR/Cas9-mediated gene inactivation. We showed that miR-187-3p is expressed in oocytes and granulosa cells in the ovary, and in discrete brain areas. Its loss-of-function led to a significant reduction in female fecundity. High-resolution 3D imaging of whole ovaries revealed that mir-187 mutants accumulate early stage I follicles and fewer advanced follicles, suggesting a defect in follicle growth. Transcriptomic profiling of mutant ovaries revealed extensive gene-expression changes consistent with the altered follicular-stage composition, including downregulation of key regulators of steroidogenesis, Wnt/β-catenin signaling, and TGF-β pathways, and upregulation of genes associated with early germ cells and immature ovarian states. Using an expression-based target-prediction pipeline, we selected several putative miR-187-3p targets, including nr6a1a ( gcnf ) and dpagt1 , two genes previously implicated in oocyte differentiation and female fertility in mammals. Together, our results demonstrate that miR-187 acts as a previously unrecognized regulator of early folliculogenesis and female reproductive capacity in medaka, expanding the repertoire of miRNAs with essential in vivo roles in teleost oogenesis and female fecundity.

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

Reconstructing a map of intrafollicular interactions provides novel insights and important clues for understanding cellular and molecular mechanisms that fine-tune antral folliculogenesis and offers a roadmap for predicting candidate factors that can be used for optimizing mammalian in vitro embryo production systems.

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.

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).