Fig. 2
From: Looking beyond the thrombus: essentials of pulmonary artery imaging on CT
a Illustrations depicting the developing six paired aortic arches with the left and right dorsal aorta during early embryogenesis. b Further development leads to formation of right and left pulmonary arteries from the sixth aortic arches, primitive truncus arteriosus and adjacent arteries. Arrest in this normal development can lead to agenesis, partial agenesis, pulmonary sling, etc.