
Respiratory bronchiole
When the wall of a terminal bronchiole becomes interrupted by alveoli, the resulting structure is termed a respiratory bronchiole because gaseous exchange occurs at the level of the alveoli. This image shows a terminal bronchiole becoming a respiratory bronchiole with three attached alveoli. 40x

Terminal bronchiole
When the wall of a terminal bronchiole becomes interrupted by alveoli, the resulting structure is termed a respiratory bronchiole because gaseous exchange occurs at the level of the alveoli. This image shows a terminal bronchiole becoming a respiratory bronchiole with three attached alveoli. 40x

Respiratory bronchiole
When the wall of a terminal bronchiole becomes interrupted by alveoli, the resulting structure is termed a respiratory bronchiole because gaseous exchange occurs at the level of the alveoli. This image shows a terminal bronchiole becoming a respiratory bronchiole with three attached alveoli. 40x

Pulmonary arteries
When the wall of a terminal bronchiole becomes interrupted by alveoli, the resulting structure is termed a respiratory bronchiole because gaseous exchange occurs at the level of the alveoli. This image shows a terminal bronchiole becoming a respiratory bronchiole with three attached alveoli. 40x

Alveoli >
Three alveoli (black X’s) form an integral part of this respiratory bronchiole. Surrounding alveoli (blue X’s) belong to other respiratory bronchioles or alveolar ducts.

Macrophages >
Macrophages, filled with phagocytosed black carbon particles, are located in the connective tissue surrounding the respiratory passageways.