The development of in vitro embryo production in the horse.
Authors: Morris L H A
Journal: Equine veterinary journal
Summary
# Editorial Summary: In Vitro Embryo Production in the Horse Morris's 2018 review charts the remarkable evolution of equine embryo production techniques, particularly intracytoplasmic sperm injection (ICSI), from an experimental curiosity five decades ago to an established commercial tool in modern breeding programmes. Over the past two decades, enhanced knowledge of oocyte and embryo competence has systematically resolved early technical barriers, allowing practitioners to achieve consistently high nuclear maturation and cleavage rates in vitro. The critical bottleneck currently limiting widespread adoption remains the relatively low blastocyst development rate, though embryos that do reach this stage demonstrate impressive clinical performance, with post-transfer pregnancy rates exceeding 60%. For equine professionals involved in reproductive management—particularly those supporting high-value breeding stock or mares with fertility complications—these developments offer viable alternatives to conventional breeding, though success ultimately depends on optimising laboratory culture conditions to improve blastocyst formation. Understanding both the capabilities and present limitations of ICSI technology enables better-informed discussions with breeders about realistic timelines, costs, and the selection criteria that favour successful outcomes.
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Practical Takeaways
- •ICSI and in vitro embryo production are now established commercial options for equine breeders seeking to maximize genetic potential or overcome subfertility
- •While blastocyst development rates remain suboptimal, those embryos that do reach blastocyst stage show strong viability with success rates comparable to conventional embryo transfer programs
- •Continued refinement of oocyte maturation and embryo culture protocols offers potential for further improvements in the efficiency and accessibility of this technology
Key Findings
- •In vitro embryo production technology has progressed rapidly over 20 years to become commercially viable for equine breeding
- •High nuclear maturation and cleavage rates are now achievable in vitro, with low blastocyst development being the primary limiting factor
- •In vitro-derived blastocysts achieve pregnancy rates exceeding 60% following transfer to recipient mares
- •Improved understanding of oocyte and embryo competence in horses has been critical to overcoming initial ICSI-related technical challenges