![This is blank.](https://digitalhistology.org/wp-content/themes/histology-unified/imgs/trans.png)
Secondary bronchus
A secondary bronchus resembles a primary bronchus except that all layers are thinner; the passageway is surrounded by plates rather than rings of cartilage; and the smooth muscle becomes more prominent. Abundant, longitudinal elastic fibers remain in the lamina propria, but they are more dispersed than in the trachea and primary bronchi. 200x
![Epithelium > <p>The epithelium of a secondary bronchus is pseudostratified columnar with cilia and goblet cells. The lamina propria is rich in elastic fibers, and smooth muscle bands spiral around the bronchus.</p>](https://digitalhistology.org/wp-content/uploads/2018/06/O.R.I.C.SB_.03.P01.png)
Epithelium >
The epithelium of a secondary bronchus is pseudostratified columnar with cilia and goblet cells. The lamina propria is rich in elastic fibers, and smooth muscle bands spiral around the bronchus.
![Lamina propria <p>The epithelium of a secondary bronchus is pseudostratified columnar with cilia and goblet cells. The lamina propria is rich in elastic fibers, and smooth muscle bands spiral around the bronchus.</p>](https://digitalhistology.org/wp-content/uploads/2018/07/O.R.I.C.SB_.03.P02.png)
Lamina propria
The epithelium of a secondary bronchus is pseudostratified columnar with cilia and goblet cells. The lamina propria is rich in elastic fibers, and smooth muscle bands spiral around the bronchus.
![- Smooth muscle <p>The epithelium of a secondary bronchus is pseudostratified columnar with cilia and goblet cells. The lamina propria is rich in elastic fibers, and smooth muscle bands spiral around the bronchus.</p>](https://digitalhistology.org/wp-content/uploads/2018/06/O.R.I.C.SB_.03.P03.png)
- Smooth muscle
The epithelium of a secondary bronchus is pseudostratified columnar with cilia and goblet cells. The lamina propria is rich in elastic fibers, and smooth muscle bands spiral around the bronchus.
![- Mixed glands > <p>Mixed glands are visible in the lamina propria of the secondary bronchus as well as spilling around the cartilage plates.</p>](https://digitalhistology.org/wp-content/uploads/2018/07/O.R.I.C.SB_.03.P04.png)
- Mixed glands >
Mixed glands are visible in the lamina propria of the secondary bronchus as well as spilling around the cartilage plates.
![Cartilage plates > <p>Cartilage plates, rather than cartilage rings, maintain patency in a secondary bronchus.</p>](https://digitalhistology.org/wp-content/uploads/2018/06/O.R.I.C.SB_.03.P06.png)
Cartilage plates >
Cartilage plates, rather than cartilage rings, maintain patency in a secondary bronchus.
![Bronchial blood vessels > <p>Bronchial blood vessels lie within the wall of each secondary bronchus, supplying the tissues of the wall.</p>](https://digitalhistology.org/wp-content/uploads/2018/06/O.R.I.C.SB_.03.P07.png)
Bronchial blood vessels >
Bronchial blood vessels lie within the wall of each secondary bronchus, supplying the tissues of the wall.
![Alveoli > <p>Alveoli surrounding this secondary bronchus indicate that this passageway is intrapulmonary.</p>](https://digitalhistology.org/wp-content/uploads/2018/06/O.R.I.C.SB_.03.P08.png)
Alveoli >
Alveoli surrounding this secondary bronchus indicate that this passageway is intrapulmonary.