Duplex quantification of Oct4 / Xist transcripts in series of single blastomeres from female 8-cell embryos. Xist and Oct4 RNA+DNA copy numbers measured in all cells recovered from five female 8-cell embryos (A to E). Cells were arranged and numbered based on increasing Xist template content (yellow bars). The respective Oct4 template content of each cell is shown by the green bar adjoining the yellow bar. Relative Oct4 and Xist expression patterns were variable from embryo to embryo, but specific cells contained predominantly one of the two transcripts.