Effects of the timing of the first cell division on preimplantation of fertilized mouse embryos

Abstract

Preimplantation development is a process in which an embryo develops from zygote to blastocyst. Normally, good quality embryos divide into two-cell at 24 h, four-cell at 36 h, eight-cell at 48 h, morula at 72 h and blastocyst at 96 h. However, some embryos delay their division. Therefore, the question raised here is that does this delay lead to some consequences? Despite many researches about first cell division, there are little studies on the effects of timing of it on the future development and the quality of the embryos. In this study, effects of the timing of the first differentiation of fertilized mouse zygote on the developmental ability and embryo quality during preimplantation development was examined. Embryos was divided into 2 groups to study about preimplantation and stained at expanded blastocysts to determine the quality of the embryos. The results showed that early cell division can improve the percentage of embryos developing to blastocysts and also the number of ICM in embryos. On the other hand, late cell division reduce the number of embryos developing to full-term and the embryo quality. Key words: In vitro fertilization, mouse embryos, in vitro culture, preimplantation development, timing of the first cell division, embryo quality