This slide demonstrates the different layers that form the trachea.

Clinical Case

You are asked to do an autopsy on a patient whom has died from a possible asthma attack. The patient's breathing became audibly harsh, and wheezing in both phases of respiration became prominent with prolonged expiration. This was followed by a loss of adventitial breath sounds, and the wheezing became very high pitched. The most striking feature at autopsy was the gross overdistention of the lungs and their failure to collapse when the pleural cavities were opened. When the lungs were cut, numerous gelatinous plugs of exudate were found in most of the bronchial branches down to the terminal bronchioles. Histological examination showed hypertrophy of the bronchial smooth muscle, hyperplasia of mucosal and submucosal vessels, mucosal oedema, denudation of the surface epithelium, pronounced thickening of the basement membrane, and eosinophilic infiltrates in the bronchial wall. List the layers of the trachea from outside to inside. Explain the divisions of bronchial tree. How would you distinguish between the epithelium of a bronchus and a bronchiole? Where would you find the cells of Clara and what is their function? How is the smooth muscle arranged in the airways? Which layer of the bronchial wall is probably responsible for the oedema and why? Which connective tissue fibre would you expect to find in abundance in the wall of the bronchiole?

This is a very low magnification of the trachea illustrating the different layers and lumen. Fig 73-001

This is a very high magnification of the epithelium and subjacent connective tissue of the trachea illustrating the different cells and structures. Fig 73-002

This is a low magnification of the trachea illustrating the layers of the paries membranaceus. Fig 73-003

Memorandum
Clinical Case	Fig 73-001	Fig 73-002	Fig 73-003