Abstract: The ovary is among the earliest organs to undergo age-related degeneration, limiting the reproductive potential of elite horses and constraining the growth of the equine industry. Follicular development during estrus is a key determinant of fertility, yet the molecular mechanisms underlying its decline, particularly at the level of specific ovarian cell types, remain poorly understood in equids. Here, we constructed a single-cell transcriptomic atlas to investigate ovarian changes in Kazakh horses. Using single-cell RNA sequencing (scRNA-seq), we profiled 112,861 cells from follicle-containing and follicle-absent ovaries, identifying nine distinct ovarian cell types and their subtypes, each with distinct gene expression signatures. Functional enrichment analyses revealed cell type-specific engagement in biological pathways, including ECM-receptor interaction, PI3K-Akt signaling, and oxytocin signaling. Gene expression patterns indicated tightly regulated processes of ovarian activation and cell differentiation. Notably, stromal cells exhibited high expression of , , and , while smooth muscle cells (SMCs) were marked by elevated levels of , , and . Moreover, cell-cell interaction analyses revealed robust signaling interactions among SMCs, endothelial cells, neurons, and proliferating (cycling) cells. Together, these findings provide a comprehensive single-cell transcriptomic map of normal and abnormal ovarian states during estrus in Kazakh horses, offering novel insights into the cellular mechanisms of follicular development and identifying potential diagnostic biomarkers and therapeutic targets for ovarian quiescence in equids.
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Overview
This study used single-cell RNA sequencing to map and characterize cellular changes in the ovaries of Kazakh horses during estrus, focusing on identifying abnormal features that may impact fertility.
The research provides a detailed cellular and molecular atlas, highlighting key pathways and cell interactions involved in follicular development and ovarian function.
Introduction and Background
The ovary is one of the first organs to show age-related decline, which reduces the reproductive capability of elite horses and affects the equine industry’s growth.
Follicular development during the estrus phase is critical for fertility, but detailed molecular insights at the level of specific ovarian cell types in horses are limited.
Kazakh horses represent an important breed, making the study of their ovarian physiology especially relevant to improving breeding and reproductive outcomes.
Methodology
The researchers used single-cell RNA sequencing (scRNA-seq) technology to profile individual cells from ovaries in two conditions: follicle-containing and follicle-absent (presumably abnormal or aged) ovaries.
A total of 112,861 cells were analyzed, allowing a high-resolution view of cellular diversity within the ovary during estrus.
Data processing identified nine distinct ovarian cell types and multiple subtypes, each defined by unique gene expression patterns.
Key Findings: Cell Types and Gene Expression
The nine identified ovarian cell types included stromal cells, smooth muscle cells (SMCs), endothelial cells, neurons, proliferating cells, and others, each with specific functional signatures.
Functional enrichment analyses linked these cell types to biological pathways such as:
ECM-receptor interaction (important for extracellular matrix and cellular communications)
PI3K-Akt signaling pathway (key in cell growth, proliferation, and survival)
Oxytocin signaling (known for roles in reproduction and cell signaling)
Gene expression studies demonstrated tightly regulated ovarian activation and differentiation processes during the estrus phase.
Specific markers were identified for stromal cells and SMCs, indicating their unique molecular roles (though the actual marker gene names were missing in the abstract).
Cell-Cell Interaction and Signaling
Interactions among smooth muscle cells, endothelial cells, neurons, and proliferating cells were found to be robust, suggesting a tightly coordinated network critical for normal ovarian function.
These intercellular communications likely influence follicular development, vascular regulation, and tissue remodeling within the ovary during estrus.
Significance and Implications
The creation of this single-cell transcriptomic atlas provides a comprehensive reference for normal versus abnormal ovarian states in Kazakh horses.
Insights from the study may:
Advance understanding of molecular mechanisms underlying follicular development decline and ovarian aging
Identify potential diagnostic biomarkers that could indicate ovarian quiescence or dysfunction
Guide development of targeted therapies to improve fertility and ovarian health in equids
This research fills a critical gap in equine reproductive biology with potential applications in breeding programs and veterinary medicine.
Conclusion
The study successfully applies cutting-edge single-cell transcriptomics to explore ovarian cell heterogeneity and molecular dynamics during estrus in Kazakh horses.
It lays a foundation for future functional studies and interventions to address ovarian dysfunction and optimize reproductive efficiency in horses.
Cite This Article
APA
Ren W, Zhou J, Zhu J, Zhang J, Zhao X, Yao X.
(2025).
Exploring the Abnormal Characteristics of the Ovaries During the Estrus Period of Kazakh Horses Based on Single-Cell Transcriptome Technology.
Biology (Basel), 14(10), 1351.
https://doi.org/10.3390/biology14101351
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