HBE is required for activation of <i>Nodal</i> in the early mouse embryo.

<p>Detection of mCherry (A, B, C, and D) and YFP (A′, B′, C′, and D′) in E4.5 (A–B″) or E6.5 (C–D″) aggregation chimeras generated from <i>Nodal<sup>condHBE-YFP</sup></i> (A–A″ and C–C″) or <i>Nodal<sup>ΔHBE-YFP</sup></i> (B–B″ and D–D″) ES cells and WT embryos. Images are single confocal sections. Cortical actin in blue. <i>n</i> is the number of representative embryos on the total number of embryos analyzed. Scale bar, 25 µm for E4.5 embryos and 50 µm for E6.5 embryos.</p>