Ultrastructural studies of elastase-induced experimental emphysema.

Experimental emphysema in the guinea pig was made by intracheal instillation of porcine pancreatic elastase in order to analyze the proteolytic factors related to the pathogenesis of pulmonary emphysema. Ultrastructural and morphometric studies were performed in the elastase-induced emphysema in vivo. The following results were obtained: 1) Ultrastructural studies in vivo revealed that interstitial edema and degradation of fibrous tissue already occurred 2 hours after elastase instillation. Subsequently we observed fragmentations of elastin and dissociation between elastic tissue and collagen fibers 2 days later. Apparent degradation and fragmentation of elastin was found after 7 days. 2) Morphometric studies by electron microscope on elastase-induced experimental emphysema showed significant degradation of elastin fragments. Thus, it was suggested the importance of elastolytic process on the pathogenesis of pulmonary emphysema.