The Cartilage of the Intrapulmonary Bronchi in Normal Lungs, in Bronchiectasis, and in Massive Collapse

The descriptions of the lung during the latter half of the last century, notably by Aeby (1880) and Ewart (1889),.and also the more modern work by Miller (1947) and Engel (1947) give descriptions of the cartilages in the trachea, carina, and main bronchi, but are disappointing in their lack of detailed information about the carti- lages in the intrapulmonary bronchi.On this subject the authors have concerned themselves with the determination of the size of bronchi at which cartilage dis- appears.Some have also attempted an estimate of the distance of this point from the hilum.Miller states that he found cartilage disappeared from the bronchial tree when the tubes were on an average between 0.6 and 0.7 mm.diameter.His summary of the results of other workers gave figures which ranged between 0.4 mm.(Frankenhauser) and 1 mm. (Krause and others).In a previous paper (page 89) we have shown the limited significance of measurements of bronchial diameter, especially as indications of position in the bronchial tree, and one aim of this paper is the reassessment of the point of disap- pearance of cartilage in terms of the number of bronchial generations from the hilum.Dissections were also made to show the gradation in the amount of cartilage along the wall of a bronchus and the shape and arrangement of cartilage at points of bronchial division.Horner (1839) and King (1840) described " saddle-shaped car- tilages" and Miller (1947) has described also a circular type which he found in the lungs of man.The present paper also records the results of our examination of the bronchial cartilages in bronchiectasis.Indeed it was here that our investigations began, for it was while studying specimens of this disease, particularly those associated with massive collapse, that our interest in the bronchial cartilages was aroused and we realized that their normal anatomy had been incompletely described.Finally, some aspects of the significance of the bronchial cartilages in pulmonary pathology will be discussed. METHODS OF INVESTIGATIONBoth lungs from 12 cadavers preserved by the injection of formalin into the body in the Anatomy School at the University of Melbourne were examined and found only suitable for the study of the cartilages in the proximal bronchi.Pathological changes