What is special about the pulmonary arteries and pulmonary veins?

Answer:
What makes these blood vessels unusual is that the pulmonary artery carries deoxygenated blood (instead of oxygenated), and the pulmonary vein transports oxygenated blood, not oxygen-poor.
First answer by Cowleya. Last edit by Cowleya. Contributor trust: 324 [recommend contributor recommended]. Question popularity: 2 [recommend question].