Distribution of the pulmonary artery and vein of the orangutan lung

The distribution of the pulmonary artery and vein of the orangutan lung was examined. The right pulmonary artery runs obliquely across the ventral side of the right bronchus at the caudally to the right upper lobe bronchiole. It then runs across the dorsal side of the right middle lobe bronchiole. Thereafter it runs obliquely across the dorsal side of the right bronchus, and then along the dorso-medial side of the right bronchus. This course is different from that in other mammals. During its course, it gives off branches which run mainly along the dorsal or lateral side of each bronchiole. The left pulmonary artery runs across the dorsal side of the left middle lobe bronchiole, then along the dorso-lateral side of the left bronchus, giving off branches which run along each bronchiole. The pulmonary veins run mainly the ventral or medial side of, along or between the bronchioles. In the left lung, the left middle lobe vein has two trunks; one enters the left atrium, and the other enters the left lower lobe pulmonary venous trunk. This is also different from that found in most mammals. Finally, the pulmonary veins enter the left atrium with four large veins.