163 HYPERACTIVATION OF STALLION SPERM IN FOLLICULAR FLUID FOR IN VITRO FERTILIZATION OF EQUINE OOCYTES
Authors: Lange-Consiglio A., Cremonesi F.
Journal: Reproduction, Fertility and Development
Summary
# Editorial Summary: Hyperactivation of Stallion Sperm in Follicular Fluid for Equine IVF Equine in vitro fertilisation has consistently failed due to poor sperm penetration rates, likely because laboratory conditions cannot adequately capacitate or hyperactivate sperm in the way the mare's reproductive tract does naturally. Lange-Consiglio and Cremonesi investigated whether follicular fluid (FF) harvested from preovulatory follicles could trigger the hyperactivation and acrosome reaction necessary for successful fertilisation, using swim-up-selected spermatozoa incubated in either capacitating medium alone or medium supplemented with FF. After 4 hours of FF exposure, sperm demonstrated significantly reduced straight-line velocity, straightness and linearity (hallmarks of hyperactivation), alongside the highest acrosome reaction rate (29.44%) and lowest apoptosis rate (16.93%), with the protein-bound progesterone in FF emerging as the critical trigger. Remarkably, FF-treated sperm supported the production of reproducible 8-cell-stage embryos at 18.56% success, whilst sperm incubated without FF failed to fertilise entirely (0%). For practitioners involved in equine reproduction, these findings suggest that follicular fluid constituents—particularly progesterone—are essential mediators of sperm preparation and merit consideration in optimising laboratory conditions for equine breeding programmes and assisted reproduction protocols.
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Practical Takeaways
- •Follicular fluid from estrous mares can be used as a practical tool to improve sperm preparation for equine IVF procedures in clinical practice
- •The 4-hour incubation window with follicular fluid appears optimal for achieving both hyperactivation and acrosome reaction before oocyte exposure
- •This protocol demonstrates reproducible embryo production (18.56%) and may be applicable to stallion fertility evaluation and assisted reproductive programs
Key Findings
- •Follicular fluid treatment induced hyperactivation in stallion sperm with 29.44% acrosome reaction rate at 4 hours incubation
- •IVF coupling capacitation with follicular fluid hyperactivation achieved 18.56% 8-cell stage embryo development versus 0% without follicular fluid
- •Follicular fluid did not impair sperm viability while reducing apoptosis rate to 16.93%
- •Sperm incubated in capacitating medium alone without follicular fluid showed zero fertilization success