Abstract
The anatomical investigation about the respiratory bronchioles which branch from pre-terminal bronchioles was performed with an inflated-fixed human lung specimen. Eight lung blocks obtained from a normal fixed lung were cut into slices 0.5mm thick and were radiographed in contact with a fine grain film. The radiographs were digitalized and magnified by the image analyzing machine and tracing procedure of intralobular bronchiole was performed with the magnified radiographs. In this study, we examined thirty-six secondary pulmonary lobules in the subpleural area, and we found that the number of respiratory bronchioles branching from pre-terminal bronchioles ranged from 0 to 6 with an average of 1.6 per one lobule. Although these respiratory bronchioles could be observed in any branching generation in secondary lobules, we found that these branches, especially those with retrograde courses, supplied the proximal portions of the lobules in about 36% of cases. According to these facts, we conclude that respiratory bronchioles branching from pre-terminal bronchioles can be considered as daughter branches of the lobule and have a role to supply the proximal portion of the lobule.
