Bronchial cartilage in chronic bronchitis.

An examination has been made of the amount of bronchial cartilage in the subsegmental bronchi of nine chronic bronchitics and seven controls. The axial pathway in four or five representative bronchopulmonary segments were carefully dissected in each lung. In each segment the mean extent of cartilage arranged circumferentially in the walls of the bronchi was significantly less in the chronic bronchitic patient than in the controls. Of the 42 specimens from the various bronchopulmonary segments of the controls, the cartilage was arranged circumferentially to the fifth generation or further in 33, but extended this far in only 14 of the 50 specimens from the chronic bronchitics. Using certain defined criteria, deficiency of cartilage was found in 25 of 50 specimens from 11 lungs of the chronic bronchitics and in only one of 42 specimens from nine control lungs. There was a negative correlation between the degree of bronchial gland enlargement, as measured by the gland/wall ratio, and the average extent of circumferentially arranged cartilage along the bronchi (r=−0·8, p<0·01). Similarly, the number of bronchopulmonary segments affected increased and the average extent of circumferentially arranged cartilage decreased with increase in severity of the bronchitis. We think that the deficiency of bronchial cartilage in chronic bronchitics would favour collapse of the affected bronchi during forceful expiration or cough.