3. Trachea:-
•Trachea is lined by a ciliated pseudodtratified columnar epithelium with goblet
cells.
•A lamina propria and submucosa lie below the epithelium,but are not clearly
demarcated from one another.
•Glands,mostly mixed,occur in deeper layers of lamina propria and within the
submucosa.
•Rings of hyaline cartilage which are incomplete dorsally,support the tracheal wall.
•A layer of smooth muscle,the trachealis muscle is located dorsally in the trachea.
•It is positioned internal to the gap in the
tracheal cartilages in the horse,pig and
ruminants.
It lies external to the gap in cat and dog.
•An adventitia of connective tissue
completes the wall of trachea.
8. Bronchus
•The trachea bifurcates into two primary bronchi, which enter the lung and then branch
several times to give rise to smaller secondary and tertiary bronchi.
• Bronchi differ from the trachea in having plates rather than rings of cartilage, and in having
a layer of smooth muscle between the lamina propria and submucosa.
9. 4 – Elastic band
6- Hyaline cartilage
7-lamina propria
9-mixed gland
10-muscularis
11-pseudostratified epithelium
10. Bronchioles
•Bronchioles are smaller branches of the bronchi, and are distinguished from them by
the absence of cartilage and glands.
Terminal bronchioles :-
•No cartilage but smooth muscle.
•Clara cells present .
•smallest conducting bronchioles consist of a simple cuboidal (or perhaps “low
columnar”) epithelium of mostly exocrine cells, a few ciliated cells, and NO goblet cells, and are
called terminal bronchioles .
Respiratory Bronchioles:
You might see short, transitional regions of bronchioles which have alveoli in their walls. These
bronchioles with alveoli in their walls are called respiratory bronchioles.