The bronchial tree, lobular division and blood vessels of the woodchuck (Marmota monax) lung.

The right lung of the woodchuck (Marmota monax) consists of the upper, middle, lower and accessory lobes, which are separated by interlobular fissures. The left lung consists of the middle and lower lobes, which are united to form a single lobe. In one of the two specimens examined, the left lung had a small upper lobe bronchiole. The right pulmonary artery runs along the ventrolateral side of the right bronchus crossing the ventral side of the right upper lobe bronchiole, then crosses the dorsal side of the right middle lobe bronchiole, and thereafter runs between the dorsal and lateral bronchiole systems, along the dorsolateral side of the right bronchus. During its course, the right pulmonary artery gives off branches which run along each bronchiole, mainly on the dorsal or lateral side. The left pulmonary artery runs across the dorsal side of the left middle lobe bronchiole and is distributed to the left middle and lower lobes in a manner similar to the right pulmonary artery in the right middle and lower lobes. The pulmonary veins run mainly along the medial or ventral side of the bronchioles, and between them.