Exposure to follicular fluid during oocyte maturation and oviductal fluid during post-maturation does not improve in vitro embryo production in the horse.

The research study explores whether the exposure of equine oocytes to follicular fluid during maturation and oviductal fluid during post-maturation can enhance in vitro embryo production in horses. The experiment, however, concluded that such exposure does not significantly improve the rates of in vitro maturation, fertilization, and development of equine embryos.

Research Context and Aims

• The study was conducted in the context of the extinction threat faced by numerous horse breeds, underlining the importance of genome resource banking. Cryopreservation of embryos, which effectively stores genetic material from both sexes, presents a rapid method to repopulate a breed.
• In vitro production of horse embryos allows for multiple embryos per cycle, serving as an efficient conservation mechanism. However, current techniques such as Intracytoplasmic sperm injection (ICSI) come with challenges including high costs, technical complexities, and low success rates.
• The authors aimed to determine if enhancing the in vitro environment to more closely resemble natural conditions could boost embryo production. This was tested by studying the effect of maturing the oocytes in preovulatory follicular fluid (pFF) and incubating them post-maturation in oviductal fluid (OF).

Methodology and Results

• Oocytes were gathered from mares that were slaughtered or via an ovum pick-up procedure. These oocytes were matured in vitro using either pFF or a semi-synthetic maturation medium (MM).
• The result of the experiment showed no significant difference between the in vitro maturation, fertilization and development rates of oocytes exposed to both pFF and MM. This challenges the hypothesis that exposure to physiological fluids can boost embryo production.
• Post-maturation, the oocytes were incubated with or without OF. Similarly, post-maturation exposure to OF did not impact fertilization and development rates significantly. It reaffirms the conclusion that physiological fluid exposure does not improve in vitro embryo production in horses.

The research, therefore, suggests that refining the in vitro environment to more closely represent physiological conditions may not necessarily enhance the success of horse embryo production. Future research might focus on exploring different avenues to increase the efficiency and effectiveness of in vitro equine embryo production.