Molecular changes in the equine follicle in relation to variations in antral follicle count and anti-Müllerian hormone concentrations.
Authors: Claes A, Ball B A, Troedsson M H T, Curry T E, Squires E L, Scoggin K E
Journal: Equine veterinary journal
Summary
# Editorial Summary Circulating anti-Müllerian hormone (AMH) concentrations vary considerably between mares, and this variation is thought to reflect differences in their antral follicle count (AFC) and underlying follicular function, yet little is known about how gene expression and molecular signalling within developing follicles drive these differences. Claes and colleagues examined granulosa and theca cells harvested from follicles of varying sizes across mares with different AFC and AMH profiles, quantifying expression of AMH and related regulatory genes to establish relationships between follicular development stage, ovarian reserve markers, and cellular behaviour. Mares with higher AFC and elevated circulating AMH demonstrated distinct patterns of AMH gene expression within granulosa cells, with expression levels correlating to follicle size and developmental stage rather than remaining static throughout follicular growth. These molecular findings suggest that AFC and AMH concentrations reflect genuine differences in how individual follicles develop and function at the cellular level, rather than simply representing passive variations in follicle numbers. For practitioners using AMH testing or AFC ultrasonography to assess ovarian reserve, reproductive potential, or age-related decline in mares, these results underscore that these markers capture meaningful biological differences in follicular activity—making them potentially valuable for fertility assessment, breeding decisions, and monitoring response to reproductive interventions.
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Practical Takeaways
- •AMH testing could help identify mares with different ovarian reserve and reproductive potential based on their individual AFC patterns
- •Understanding follicular molecular mechanisms may enable better prediction of reproductive performance and fertility in individual mares
- •AFC and AMH concentrations could be useful biomarkers for assessing ovarian function and breeding soundness in mare evaluations
Key Findings
- •Circulating AMH concentrations vary widely between mares and correlate with differences in antral follicle count
- •Antral follicle count may reflect variations in follicular function and regulatory mechanisms
- •Molecular changes in equine follicles are associated with AFC and AMH concentration variations during follicular development