Equine oocyte maturation with epidermal growth factor.
Authors: Lorenzo P L, Liu I K M, Carneiro G F, Conley A J, Enders A C
Journal: Equine veterinary journal
Summary
# Editorial Summary: Equine Oocyte Maturation with Epidermal Growth Factor Epidermal growth factor (EGF) enhances oocyte maturation in various species, but its role in equine reproduction had not been thoroughly characterised; this investigation sought to determine whether EGF promotes nuclear maturation in horse oocytes and to map the distribution of EGF receptors within the ovary. Researchers collected oocytes from equine follicles (15–25 mm diameter) via aspiration and aspiration-scraping, then cultured them for 36 hours in three treatment groups: unsupplemented medium (control), medium with 50 ng/ml EGF, or medium with 10% oestrous mare serum (EMS), with each further subdivided by exposure to a tyrosine kinase inhibitor at varying concentrations to establish the mechanism of action. Treatment with EGF increased the proportion of oocytes reaching metaphase II (the mature stage) to 69.4%, compared with only 26.9% in controls—a significant improvement—and the kinase inhibitor successfully suppressed this EGF-driven maturation, confirming involvement of the EGF receptor signalling pathway; notably, EGF receptors were localised predominantly in cumulus cells surrounding the oocyte rather than in mural granulosa cells. These findings establish that EGF plays a genuine physiological role in regulating equine oocyte nuclear maturation and suggest practical applications for optimising in vitro maturation protocols in equine assisted reproductive technology, particularly for breeding programmes, fertility management, and research involving embryo transfer.
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Practical Takeaways
- •EGF supplementation in oocyte culture media significantly improves in vitro maturation rates for equine assisted reproduction protocols
- •These findings support development of improved ART techniques in horses by identifying EGF as a key physiological regulator of oocyte maturation
- •Cumulus cells appear to be the primary responsive tissue to EGF signaling, which may guide optimization of oocyte collection and culture methods
Key Findings
- •EGF treatment significantly increased metaphase II stage oocytes from 26.9% (control) to 69.4% (P<0.05)
- •EGF receptor was localized in equine follicles with stronger expression in cumulus cells than mural granulosa cells
- •Tyrphostin A-47 tyrosine kinase inhibitor suppressed EGF-induced maturation, confirming EGF receptor signaling pathway involvement
- •Oocyte recovery rate was 84.6% and retrieval yield was 6.55 oocytes per mare