[Co-culture of mouse blastocysts and their epigenetic modification]

To discuss the effect of co-culture on the quality of mouse blastocysts and their epigenetic modification. We divided mouse zygotes into three co-culture experiment groups : with granular cells (group I ), oviduct epithelium cells (group II) and oviduct tissue (group III). Meanwhile, we set up control A (cultured in vitro, only KSOM (KCl+ simplex optimized medium)) and control B (cultured in vivo). Then we compared cleavage rate and blastocyst rate among different groups. After that we evaluated the quality of blastocysts by using ICM/TE (Inner cell mass/Trophectoderm cells) ratio via staining with propidium iodide and Hoechest333258, and analyzed the level of genome methylation and histone acetylation by immunofluorescence. Compared with the control group A, the co-culture groups had increased cleavage rate and blastocyst rate (P < 0.05), blastocyst cells and the ICM/TE ratio of co-culture groups were higher (P < 0.05), the level of genome methylation and histone acetylation had no significant difference between groups in vitro (P > 0.05), but the level of genome methylation in vivo was significantly higher than that of in vitro (P < 0.05). The co-culture methods can successfully promote the development rate of embryos in vitro, and improve the quality of the blastocyst. However, the methods have drawbacks in changing the abnormal genome methylation with in vitro culture.