Fig. 7

OFT development in Crocodylus. a In the proximal OFT the septal cushion flanking the folding septum (FS, yellow curve) is obvious. b–d Three consecutive sections in the distal OFT in which the OFT cushions are visible. The condensed mesenchyme of the aorto-pulmonary septum is indicated (*). In c at the arterial level the AP separates the pulmonary trunk from the aortic channels. The NCC (*) and SHF aorto-aortic flow divider (#) are indicated. At the ventral side, the myocardium protrudes inward (orange curve). d The arterial trunks are completely separated by the AP septum and the aortic flow divider (#). e TFAP2α-positive cells (NCC) in the wall of PAA3 (arrows), but not in the other PAAs (not shown). f 3D reconstruction of the fused OFT cushions and the PAAs (indicated by their number) including the AP septum (green*) between PAA3 + 4 and PAA6. Abbreviations as in Fig. 3