![This is blank.](https://digitalhistology.org/wp-content/themes/histology-unified/imgs/trans.png)
Transition of bronchiole to respiratory bronchiole
This image shows the transitions that occur as a bronchiole becomes a terminal bronchiole which, in turn, becomes a respiratory bronchiole. Because alveoli bud directly from the lumen of a respiratory bronchiole, this passageway is a portion of the respiratory portion of the respiratory system. 40x
![Bronchiole <p>This image shows the transitions that occur as a bronchiole becomes a terminal bronchiole which, in turn, becomes a respiratory bronchiole. Because alveoli bud directly from the lumen of a respiratory bronchiole, this passageway is a portion of the respiratory portion of the respiratory system. 40x</p>](https://digitalhistology.org/wp-content/uploads/2018/06/O.R.I.C.B.10.P01.png)
Bronchiole
This image shows the transitions that occur as a bronchiole becomes a terminal bronchiole which, in turn, becomes a respiratory bronchiole. Because alveoli bud directly from the lumen of a respiratory bronchiole, this passageway is a portion of the respiratory portion of the respiratory system. 40x
![Terminal bronchiole <p>This image shows the transitions that occur as a bronchiole becomes a terminal bronchiole which, in turn, becomes a respiratory bronchiole. Because alveoli bud directly from the lumen of a respiratory bronchiole, this passageway is a portion of the respiratory portion of the respiratory system. 40x</p>](https://digitalhistology.org/wp-content/uploads/2018/06/O.R.I.C.B.10.P02.png)
Terminal bronchiole
This image shows the transitions that occur as a bronchiole becomes a terminal bronchiole which, in turn, becomes a respiratory bronchiole. Because alveoli bud directly from the lumen of a respiratory bronchiole, this passageway is a portion of the respiratory portion of the respiratory system. 40x
![Respiratory bronchiole <p>This image shows the transitions that occur as a bronchiole becomes a terminal bronchiole which, in turn, becomes a respiratory bronchiole. Because alveoli bud directly from the lumen of a respiratory bronchiole, this passageway is a portion of the respiratory portion of the respiratory system. 40x</p>](https://digitalhistology.org/wp-content/uploads/2018/06/O.R.I.C.B.10.P03.png)
Respiratory bronchiole
This image shows the transitions that occur as a bronchiole becomes a terminal bronchiole which, in turn, becomes a respiratory bronchiole. Because alveoli bud directly from the lumen of a respiratory bronchiole, this passageway is a portion of the respiratory portion of the respiratory system. 40x
![Alveoli > <p>Many alveoli are visible. Alveoli (black Xs + arrows) whose lumens are directly continuous with the lumen of a bronchiole establish this bronchiole as a “respiratory” variety rather than “terminal,” since gaseous exchange occurs through alveolar walls. Other alveoli (blue Xs) belong to other respiratory bronchioles or alveolar ducts. </p>](https://digitalhistology.org/wp-content/uploads/2018/06/O.R.I.C.B.10.P04-1.png)
Alveoli >
Many alveoli are visible. Alveoli (black Xs + arrows) whose lumens are directly continuous with the lumen of a bronchiole establish this bronchiole as a “respiratory” variety rather than “terminal,” since gaseous exchange occurs through alveolar walls. Other alveoli (blue Xs) belong to other respiratory bronchioles or alveolar ducts.