HBE is required for activation of Nodal in the early mouse embryo.

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 NodalcondHBE-YFP (A–A″ and C–C″) or NodalΔHBE-YFP (B–B″ and D–D″) ES cells and WT embryos. Images are single confocal sections. Cortical actin in blue. n 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.