Figure 6

Increasing Xist and Oct4 expression in blastomeres of embryos progressing through the 8-cell stage. (A) Xist RNA+DNA amplification plots of single blastomeres from female embryos at the 7-cell to compacting 8-cell stages. A different color was used for each embryo analyzed; plots of cells from the same embryo are shown in the same color. Embryos were labeled as "early 8-cell" when they contained blastomere pairs still connected after cell division. They were identified as "8-cell" when cells were not connected and had well-defined boundaries, and as "compacting 8-cell" when compaction had begun and blastomere counts were finalized only after de-compaction and cell harvesting. Progression through the 8-cell stage is visualized by increasingly darker hues. Within each group, embryos slower to reach the indicated stage were assigned a lighter color than faster-developing embryos. (B) Oct4 RNA+DNA real-time PCR curves generated by single blastomeres of male and female embryos at the third cleavage stage. Color-coding followed the same criteria used for the Xist plots in panel A, but colors were used independently in the two panels. Although cells from each embryo consistently produced signals spread over several PCR cycles, overall Xist and Oct4 expression tended to increase in embryos approaching compaction, as shown by the right-to-left shift of the plots.