Timing of completion of the first meiotic division in bovine oocytes after maintenance of meiotic arrest with cycloheximide and their subsequent development.

This study examined the timing of completion of meiosis I of bovine oocytes in which meiotic resumption had been inhibited by cycloheximide (CHX), and also determined the optimum interval of maturation in culture for subsequent fertilization and development. Most oocytes treated with CHX reached metaphase II at 16 hr in the maturation culture, while control oocytes did at 20 hr. CHX-treated oocytes cultured for 16 hr were normally fertilized but failed to develop into blastocysts. Maturation in culture for 20 hr resulted in comparable development for control oocytes. The results indicate that nuclear maturation of CHX-treated oocytes was completed 4 hr faster than for control oocytes, however the same interval of maturation as that of control oocytes is necessary for subsequent development to blastocysts.