Effect of Meiotic Arrest by Cycloheximide on the In Vitro Maturation of Bovine Oocytes and Their Subsequent Development Following In Vitro Fertilization

Cycloheximide (CHX) is a reversible inhibitor of bovine meiotic resumption. This study examined the timing of nuclear maturation in bovine oocytes treated with CHX and determined the optimum maturation interval in cultures for their subsequent development. CHX prevented the nuclear maturation of nearly all oocytes for 24 h. In an inhibitor-free medium, the majority of the CHX-treated oocytes underwent germinal vesicle breakdown (GVBD) after 6 h of culture, while the control oocytes did so at 10 h. In the maturation culture, the majority of the CHX-treated oocytes had reached metaphase II by 16 h whereas the control oocytes took 20 h. However, the CHX-treated oocytes that matured for 16 h developed into blastocysts at low rates while those that were matured for 20 h had a development rate similar to that of the control oocytes. These results indicate that the nuclear maturation of CHX-treated oocytes did accelerate, but these oocytes needed the same maturation time as required by the control oocytes for their subsequent development to blastocysts.