Received February 20, 2013
Accepted March 03, 2013

Objective: To evaluate the impact of in vivo superovulation on early embryonic development in a rat model. Methods: Experiment 1: Female Wistar rats were superovulated with injection of PMSG followed by hCG 48 hours later. Embryos were collected 24 h after hCG administration. Experiment 2: Female Wistar rats (n=16) were distrbuted to a control or superovulated group. Embryos were collected 48 and 72 h after hCG administration. The total number of embryonic structures and the embryo quality grades were analyzed by Chi-squared test. Between-group differences in ovarian weight were assessed by Student’s t-test. Results: Experiment 1: 931 embryos were collected from 66 animals, with a mean of 16.3±9.5 structures per animal. The superovulation was successful in 89.4% of the animals, and 98.2% of the embryos collected from superovulated animals were viable. Experiment 2: The superovulated group had heavierovaries and produced more embryos than the control group (P < 0.001); however, these embryos contained fewer cells than controls at 72 hours after hCG administration (P<0.001). A greater percentage of embryos from the superovulated group were classified as grade I or grade II relative to embryos from the control group (P < 0.001 and P = 0.008, respectively). Conclusion: Superovulation was successful in the Wistar rat model and resulted in a greater number of embryos collected per animal. However, embryos produced as a result of superovulation developed more slowly than control embryos.