Effect of population density on the early post-implantation mouse embryo growth in vitro

Objective: To investigate the relationship between embryo population density and embryo development in vitro. Methods: Swiss Webster albino mice were used and blastocysts were flushed from the uterine horns. Various numbers of blastocysts were randomly assigned to separate 35 mm dishes and cultured for 9 days. Results: The effect of duration of culture to the mean success rates was different as the number of embryos in the dish was changed. In early egg cylinder (EEC) stage; the mean success rate was a flat function of the number of embryos. But the mean success rate was a decreasing function in late egg cylinder (LEG) stage and the decreasing rate was faster in early somite (ES) stage. Interestingly, the mean success rate to ES stage was nearly constant when more than 10 embryos were cultured in one dish. Conclusion: The success rate to each developmental stage in vitro decreased as the number of embryos in the dish and the duration of culture increased.