Fig. 3. Gene transcription is essential for preimplantation development. (A) Eight-cell stage embryos were treated with actinomycin D (0.05 µg/ml or 0.5 µg/ml), and compared with control embryos (0 µg/ml) at morula stage (upper panel). In addition, morula stage embryos were treated with actinomycin D, and observed at blastocyst stage (lower panel). Low and high magnifications are shown. (B) Hierarchical clustering analysis. The transcripts used in this analysis were increased or decreased by SB203580, SP600125 or U0126 at least by twofold over baseline (wild type). (C) The transcripts were classified into six groups based on the sensitivity to the drugs as shown. The numbers of transcripts in each group in each experiment are shown (upper). The numbers of the transcripts that were classified into each group in at least two out of the three independent experiments are shown (lower).