Roles of GDF9 and BMP15 in equine follicular development: in vivo content and in vitro effects of IGF1 and cortisol on granulosa cells.

Summary

# Editorial Summary Understanding how equine oocytes develop and acquire the capacity for normal fertilisation and embryonic development has long challenged reproductive specialists, yet the signalling molecules governing this process remain poorly characterised in horses. Abbasi and colleagues investigated the expression patterns and localisation of growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15)—oocyte-secreted factors known to regulate follicular development in other species—within equine ovarian tissue, alongside the direct effects of physiologically relevant stimuli (insulin-like growth factor 1 and cortisol) on granulosa cell function in vitro. Their findings establish GDF9 and BMP15 as key regulatory molecules in equine follicle development, with implications for how metabolic stress and systemic hormonal status may influence fertility through paracrine signalling between the oocyte and its surrounding somatic cells. These insights are particularly relevant for practitioners managing mares during intensive training or nutritional challenge, as they suggest mechanistic pathways through which energy balance and stress responsiveness directly impact oocyte competence and embryonic viability. The work provides a foundation for developing targeted interventions—whether nutritional, pharmaceutical, or management-based—to optimise reproductive outcomes in performance mares and breeding animals.

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Key Findings

• •GDF9 and BMP15 expression and localization were characterized in equine ovarian tissue for the first time
• •IGF1 and cortisol demonstrated dose-dependent effects on granulosa cell function in vitro
• •Oocyte-secreted factors play a regulatory role in equine follicle development comparable to other species

Conditions Studied

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