Abstract：Superovulation is one of important methods for obtaining oocytes, zygotes and embryos of different developmental stages. In order to investigate the effect of superovulation at different starting time on course of ovulation, fertilization and embryonic development, Kunming mouse(Mus musculus) in proestrus were superovulated by injecting pregnant mare serum gonadotropin(PMSG) at 12:00, 16:00, 20:00 and 24:00, respectively, followed by injecting human chorionic gonadotropin(hCG) 48 h later. And then, superovulated mice mated with male overnight, and vagina plugs were detected at the next morning. The results of oocytes, zygotes and embryos collected in different time after injection of hCG showed: For mouse superovulated at 12:00, 16:00, 20:00 and 24:00, the opportune times to collect oocytes from oviduct were about 16.23, 14.02, 15.93 and 12.98 h after injection of hCG, respectively; The opportune times to collect zygote were 24.62, 23.60, 26.53 and 20.03 h after injection of hCG, respectively; The opportune times to collect cleavage embryos were 42.76, 42.39, 41.85 and 40.47 h after injection of hCG, respectively; The opportune times to collect 4-cell embryos were 56.87, 57.84, 57.31 and 56.92 h after injection of hCG, respectively; The opportune times to collect 8-cell embryos were 66.89, 67.39, 66.20 and 66.07 h after injection of hCG, respectively; The opportune times to collect morulae were 76.31, 76.21, 76.29 and 75.11 h after injection of hCG, respectively; The opportune times to collect blastocysts were 100.65, 97.14, 93.91 and 96.86 h after injection of hCG, respectively; The opportune times to collect hatched blastocysts were 114.57, 112.34, 112.11 and 110.28 h after injection of hCG, respectively. In conclusion, the starting time of superovulation had no significant effect on course of ovulation, fertilization and embryo development. By regulating superovulation starting time, the appropriate time to collect oocytes, zygotes and embryos in different developmental stage could be selected. Mouse could be superovulated at a reasonable starting time to satisfy different research requirement. This study provides technical support for research involving in mouse oocytes, zygotes and embryos in accurate developmental stage.
