Use of excised ovaries for oocyte recovery by ultrasound guided follicular aspiration – Validation of an experimental model for research purposes in live mares ovum pick up.

The research focused on comparing the effectiveness of egg cell (or oocyte) recovery methods in live mares and in postmortem ovaries. The aim was to establish a reliable research model for assessing the efficiency of egg cell recovery or ovum pick-up (OPU) in horses.

Background of the Study

• The study builds on ovum pick-up (OPU), which is a frequently practised reproductive method, used to recover oocyte and produce horse embryos in vitro – in a lab, rather than inside a living body.
• However, there’s not enough knowledge on the factors influencing oocyte recovery in OPU from live mares. Therefore, the research seeks to provide credible data to this end.

Methodology

• The experiment involved a comparison of oocyte recovery in live mares and postmortem excised ovaries. Data was collected from OPU performed on 12 mares from a commercial program, while for the postmortem count, 13 excised ovaries from slaughtered mares were used.
• To maintain consistency, the same operator using the same equipment and OPU technique worked on both groups.
• The key comparison data were on the number of follicles, oocyte recovery, and oocyte morphology.

Results

• The research found a higher percentage (63.2%) of oocytes recovered per aspirated follicle in the postmortem group than the live mares group (52.9%).
• The presence of expanded cumulus oocyte complexes was also greater in the postmortem group, as compared to the live mare group.

Conclusion and Implications

• From these results, the researchers inferred that there is still potential to improve the current in vivo OPU techniques since the postmortem approach showed a significantly higher recovery rate.
• An interesting find was the presence of oocytes in the leaked fluid which overflowed during the follicle flushing of postmortem ovaries, indicating that oocyte leakage could be an overlooked factor during live OPU procedures.
• Therefore, using postmortem excised ovaries offer a promising avenue for future research to enhance oocyte recovery rates, findings that are crucial in assisted reproductive techniques in horses.