Transition of terminal to respiratory bronchiole

The transition of a terminal bronchiole (conducting portion) to a respiratory bronchiole (respiratory portion) is indicated by the appearance of alveoli associated with the wall of the respiratory bronchiole. The decrease in epithelial height at this transition is demonstrated well here. 150x

The transition of a terminal bronchiole (conducting portion) to a respiratory bronchiole (respiratory portion) is indicated by the appearance of alveoli associated with the wall of the respiratory bronchiole. The decrease in epithelial height at this transition is demonstrated well here. 150x

Alveoli associated with the respiratory bronchiole are indicated by blue arrows; alveoli associated with other respiratory bronchioles, alveolar ducts or alveolar sacs are indicated by red arrows.

A branch of the pulmonary artery accompanies the respiratory passageways to supply deoxygenated blood to the alveolar capillary beds.