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Separation of Motile Bovine Spermatozoa for In Vitro Fertilization by Electrical Charge

Marcello Rubessa, Abdurraouf Gaja and Matthew B. Wheeler

Objective: Sperm selection is essential to Assisted Reproductive Technology (ART), influencing treatment outcomes and the health of the resulting offspring. Several techniques have been developed to recover a homogeneous population of highly motile sperm cells, including centrifugation gradients, swim up and filtration procedures. It is known that the head of spermatozoa has a negative electric charge, and several studies have tried to use this physiological characteristic for the selection of high quality motile sperm from frozen-thawed semen. The study aim was to design a device that would be able to separate viable, high quality sperm for IVF after thawing, using electrical characteristics of sperm. Methods: Samples of the semen solution were taken at different times from both the anode and cathode areas. The electric charges used were 0, 1, 5 and 10 volts (V), at times of 0, 5, 10 and 20 minutes. In the second phase of the experiment, to evaluate the ability of the selected sperm to fertilize oocytes, we fertilized oocytes with semen processed with either the EC (10 volts per 10 minutes) and the discontinuous gradients. Results: Concentration and motility were affected by the voltage: V0 was different from V1, V5 and V10 (P<0.0001). There were no differences when we compared the electric channel (EC) to the Percoll discontinuous gradient on cleavage rate and embryo development rate. To verify the effect of magnetic field on the ratio of sex we evaluated the embryo sex distribution: we did not find any effect on embryo sex ratio. Conclusion: In conclusion all these observations may allow for the streamlining of many IVF protocols. Further, the decreased time gametes are outside of the optimal environment of the incubator may potentially reduce the stress on the gametes during the IVF procedures. Future, work will focus on pregnancy rates of embryos produced with EC separated sperm after IVF.