The aim of this study was to evaluate the effects of progesterone and ovarian stimulation on the development and implantation rate of mouse embryos. Two-cell embryos were collected from superovulated mice and cultured in the presence of different concentrations of progesterone (0, 5, 10 and 20 ng/ml). Also other mice were rendered pregnant in unstimulated, unstimulated progesterone-injected, superovulated and superovulated progesterone-injected groups to collect the blastocysts. The number of blastocysts and implantation sites were recorded on the 4th and 7th day of pregnancy, respectively. The diameter and cell number of blastocysts were analyzed in the in vitro and in vivo groups. After 120 h culture, the percentage of hatched blastocyst embryos in control and 5, 10 and 20 ng/ml progesterone-injected groups were 63.9%, 64.2%, 64.2% and 75.6% respectively. There were significant differences between the developmental rates of embryos in the presence of 20 ng/ml progesterone and the control and other concentrations of progesterone-injected groups (P≤0.001). The in vivo blastocyst survival rate (97.68%) and implantation rate (92.06%) in the unstimulated and progesterone-injected groups were higher than in the other groups. Blastocyst cell numbers in the superovulated (128.62 ± 1.30) and superovulated progesterone-injected groups (126.88 ± 1.60) were significantly different from the control (P<0.001). The progesterone injection without ovarian induction improved the embryo survival and implantation rates, but after superovulation it did not ameliorate the negative effects of superovulation on the implantation rate.
2008 Japanese Association for Laboratory Animal Science