The Mare: A Pertinent Model for Human Assisted Reproductive Technologies?

Area of Science:

• Comparative reproductive biology
• Veterinary medicine
• Human reproductive medicine

Background:

• Horses and humans share similarities in early embryo development kinetics until the blastocyst stage.
• Significant differences exist in reproductive seasonality, menstrual cycles, and implantation timing between horses and humans.

Purpose of the Study:

• To compare assisted reproductive technologies (ART) and infertility treatments between horses and humans.
• To explore the potential for reciprocal knowledge gain in ART and infertility management.
• To evaluate the horse as a model for human ART.

Main Methods:

• Comparison of oocyte maturation, fertilization techniques (in vitro fertilization vs. intra-cytoplasmic sperm injection), embryo transfer protocols, and cryopreservation efficiencies.
• Analysis of species-specific ART procedures, including hormonal treatments and timing of interventions.

Main Results:

• Horses require in vitro oocyte maturation due to inefficient ovarian stimulation, unlike in vivo maturation in humans.
• Intra-cytoplasmic sperm injection (ICSI) is standard in horses, while both ICSI and in vitro fertilization are used in humans.
• Embryo transfer in horses is limited to blastocysts, whereas humans transfer embryos from the four-cell to blastocyst stage.
• Oocyte and embryo cryopreservation is well-established in humans but not fully mastered in horses.

Conclusions:

• While early embryo development is similar, significant ART procedural differences exist between horses and humans.
• The horse cannot serve as a singular model for human ART due to species-specific reproductive strategies.
• Comparative studies offer valuable insights into infertility and ART, benefiting both human and veterinary reproductive medicine.