THE LUNG 



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FIG. 289. A BRONCHUS FROM THE HUMAN LUNG. 



a, lining epithelium; 6, duct of a mucous gland; c, muscularis mucosse; d, accu- 

 mulated mucus, etc., bathing the surface of the epithelium; e, mucous glands; /, 

 hyaline cartilage; g, outer fibrous coat; h, pulmonary alveoli. Hematein and eosin. 

 Photo. X 34. 



developed muscularis mucosce composed of interlacing bundles of circular 

 smooth muscle fibers. This layer forms a complete muscular coat which 

 20 



