Movie 5.

HCN4 expression in 3D space for a mouse embryo at E11.5. The embryo was stained with SYTOX Green (light blue) and with antibodies to TNNI3 (yellow green) and to HCN4 (white). The atrium and common cardinal veins are positioned so as to sandwich the trachea in a V-shape. Pronounced expression of HCN4 was observed on both sides of the common cardinal veins and the right atrium. Scale bar, 200 μm.