Fig. 4

OFT development in the lizard Pogona HH22–29.5. a In the proximal OFT a thin cellularized septal cushion, flanking the folding septum and the equally indistinct parietal cushion are present. Bar = 100 µm. b The centrally located septal (sc) cushion is flanked by the parietal (pc) and intercalated (ic) cushions. Note that the condensed mesenchyme in the septal cushion is inconspicuous. c In HH28, the septal and parietal cushion have fused (*), separating the aortic and pulmonary channels. d At HH29.5, the aortic channel is not divided, yet, but a left visceral aorta (vAo) and a right systemic aorta (sAo) can be discerned. Bar = 50 µm. e Higher magnification shows some apoptotic cells in the septal cushion. f The aorto-pulmonary septum (*) separates the two aortic from the pulmonary channels, while a second separation (#) is present between both aortae. No condensed mesenchyme is visible in the AP septum. Abbreviations as in Fig. 3