A comparative study of parthenogenetic activation and in vitro fertilization of in vitro matured bovine oocytes

The objective of this study was to determine the effects of 3 chemical agents used sequentially and electrical stimuli on parthenogenetic activation of in vitro matured bovine oocytes and comparison with a standard IVF protocol for embryo developmental rates. For this purpose, oocytes were matured in tissue culture medium-199 (TCM-199) at 39 °C and 5% of CO2 in humidified air. For IVF, matured oocytes were fertilized in Modified Tyrode-Lactate Medium. In the parthenogenetic activation process, direct current (DC) was pulsed (133 V/500 μm) for 25 μs and oocytes were sequentially activated with calcium ionophore (CaI) for 10 min, cycloheximide (CHX) + cytochalasin D for 1 h, and CHX for 5 h. After that, all embryos (both IVF and parthenogenetic) were cultured in G1.3/G2.3 media containing 6% CO2, 5% O2, and 89% N2 in humidified air at 39 °C. Cleavage rate was not significantly different following parthenogenetic activation compared to IVF (P > 0.05). Morula, blastocyst development, and blastocyst cell numbers were not also significantly different between parthenogenetic activation and IVF (P > 0.05). These results showed that bovine oocyte activation with electrical stimulation and chemical agents gave the desirable results, and the culture medium (G1.3/G2.3) supported both parthenogenetic and IVF embryo development.