THE RESPIRATORY SYSTEM. 



477 



cosa assumes its normal thickness and character and the epithelium is 

 regenerated from the cells of the deeper layers. 



Various forms of bacteria may be associated with acute bronchitis, and 

 are presumably the excitants under favorable conditions of the lesions ; 

 the etiological relationship has, however, not yet been experimentally 

 established. The most common forms of bacteria are Streptococcus pyo- 

 geues, the pneuniococcus, Staphylococcus aureus, and the influenza 

 bacillus. 1 



Chronic Catarrhal Bronchitis. This form of bronchitis may be the sequel 

 of one or more attacks of acute bronchitis. More frequently it is associ- 

 ated with emphysema, heart disease, interstitial pneumonia, phthisis, 





FIG. 361. ACUTE CATARRHAL BRONCHITIS. 



This section of a small portion of the bronchial wall shows considerable exfoliation of the epithelium, 

 but many of the deeper so-called " mother cells " remain in place. There are swelling of the connective- 

 tissue cells and congestion of blood-vessels in the submucosa, with oedema and emigration of leucocytes. 

 Some of the leucocytes are passing through the epithelium to mingle with, the mucous exudate and exfoli- 

 ated cells in the lumen of the bronchus. Some of the ciliated cells show the " beaker " shape with a homo- 

 geneous interior indicating the production of mucus within them. 



pleuritic adhesions, or the inhalation of irritating substances. There is 

 in most cases a constant production of mucus, pus, and serum in consid- 

 erable quantities, and these inflammatory products may have a very foul 

 odor. Less frequently these products are very scanty dry catarrh. 

 The epithelium is deformed and desquamating, with a production of new 

 cells in the deeper layers. There may be epithelial hyperplasia or atro- 

 phy ; the mucous glands are large or atrophied ; there may be hyperpla- 

 sia or atrophy of the submucosa; the muscularis may be thickened or 

 atrophied. These changes in the fibrous and muscular elements of the 

 walls lead to the so-called " trabeculation " of their inner surfaces (Fig. 

 262). Obliterating arteritis of the associated vessels may occur. These 

 changes in the walls of the bronchi may lead to bronchiectasia. 



1 For a study of the bacteria found in bronchitis see Ritchie, Jour. Path, and Bact, 

 vol. vii., p. 1, 1900; also reference to bacteria in lungs, p. 459. 



