Fig. 2

Expression levels of four key transcription factors (TFs) in early embryogenesis. a The gene expression levels of Oct4, Cdx2, Nanog and Gata4 in the single cells of preimplantation embryos. The cells with the highest expression level of each TF are depicted in red, while the intermediate and the lowest expression levels are shown as white and blue, respectively. b The regulatory circuitry between Oct4 and Cdx2 (left), and Nanog and Gata4 (right). Green and red arrows show positive and negative regulatory interactions, respectively. TE: Trophectoderm, PE: Primitive endoderm, EPI: Epiblast