To develop individual culture system for bovine oocytes, effect of individual maturation in MWP and individual culture in WOW were examined. For investigating influence of MWP on IVM, IVF and IVC (Exp. 1), oocytes were matured individually in MWP or 10-µl droplet and in 50-µl droplet in a group as control. Nuclear maturation, fertilization and development were evaluated in all experimental groups. Maturation rates were similar in all experimental groups. After fertilization, oocytes from 10-µl droplet IVM showed significantly higher rate of enlarged sperm head compared with those of other groups even though fertilization rates of all groups were similar. Blastocyst rates of oocytes matured in MWP and in 50-µl droplets tended to be higher than that in 10-µl droplets. For investigating influence of WOW on IVC (Exp. 2), fertilized oocytes were cultured in WOW. Cleavage and blastocyst development were assessed, and effect of number of neighbor embryos (0, 3, 5 and 8) in a WOW on embryonic development was also examined. As control, 5 or 25 embryos were cultured in a 40-µl droplet. No differences of blastocyst rate were observed in all experimental groups. However, cell numbers in blastocysts of 5 embryos in droplets were significantly low. Number of adjacent embryos in a WOW dish did not affect blastocyst development and cell numbers of blastocysts. In conclusion, MWP supports the acquisition of developmental competence of individual bovine oocytes as same as conventional group maturation system. Further, WOW can provide high and stable blastocyst development in small embryo group wherever embryos are placed in micro-wells of WOW.
