(D) Stacked bar plots show the fraction of embryos at blastocyst stages after injection with different mRNA, as indicated. Error bars, mean ± S.D.; n = 3 biological replicates per group; N, total number of embryos analyzed for each condition; **P < 0.01, ***P < 0.001 as compared with control group, by two-tailed Student's  t-test. 