Bronchial tree structure in the human, beagle, rat, and hamster

Partial results of an extensive study of airway morphology are presented. Bronchial tube branching angles, lengths, and diameters were measured on replica casts of lungs from humans, dogs, rats, and a hamster. Each cast of silicone moulding compound was cured in the thorax of the subject, checked for artifacts and hand pruned before measurement. A total of about 150,000 morphometric measurements were made based on a conceptual model of airway branches. Data presented include number of divisions in the bronchial tree in various lobes, and the changes in branching geometry seen as one progresses deeper into a lobe. Significant differences in structure were found between species, from lobe-to-lobe within a lung and with depth within a lobe. The humans had bronchi that were longer in relation to their diameters and had more symmetric bifurcations with respect to diameter ratios and branch angle ratios than the other species. (U.S.)