develops from ends during starts during intermediate mesoderm arterial endothelium aorta paired dorsal aorta left dorsal aorta eriksegerdell right dorsal aorta paired dorsal aortae The embryonic right and left aortas that develop in parallel with the heart and gain access to it via the aortic arches. Later the paired dorsal aortic anlagen unite and finally form the unpaired descending aorta of the adult. 2015-05-16T14:25:29Z xenopus_anatomy XAO:0005019 NF stage 31 NF stage 44