Figure 2. Differential Hippo signaling specifies distinct cell fates in the preimplantion mouse embryo. (A) At the morula stage, mouse embryos consist of inner and outer cells. The outer cells are specified to become the trophectoderm (TE), whereas the inner cells are specified to become the inner cell mass (ICM) at the blastocyst stage. (B) In the inner cells, cell adhesion activates Hippo signaling in an Amot-dependent manner, allowing the inner cells to express ICM-specific transcription factors and adopt ICM fate. In the outer cells, Hippo signaling is suppressed by cell polarity, which specifies the outer cells to become the TE. (C) The distribution of Amot (shown in red) in normal and polarity-disrupted embryos.