A Study On Ultrastructure Of Pulmonary Surface Active Films In Lining Layer Of Lung Alveoli And Its Significance

Objective! To observe the characteristics of the ultrastructure of pulmonary surface active films in the lining of lung alveoli during respiration in normal or asthmatic guinea-pigs and reassess the role of demonstrating the ultrastructure of PS with ruthenium red (RR).[Methods! PS compound fixation was used to fix the lungs during respiration in normal or asthmatic guinea-pigs and a transmission electron microscope was used to observe the ultrastructure of pulmonary surface active films in the lining of lung alveoli.[Results! ~DThe alveolar lining layer consisted of the surface active f it. and its subphase. The surface active films appeared as uilamellar, duplex-lamellated or multilamellated osmiophilic films, uilametlar viscites, duplex-lamellated vesicles, multilamellated vesictes, lamellar bodys, tubular myelin figures, multilauiellated vesicles plus osuiophitic films, osmiophilic film plus uilaaellar visciles and so on. On the smoother parts of alveolar wall, there frequently were uitamellar or duplex-lauiellated osmiophilic films, or vesicles, but in alveolar corners or alveolar clefts, there also were lamellar bodys, tubular myelin figures, osmiophilic films plus uilamellar visciles and so on. The arrangement sequence of different PS structures in local surface active films was from more active to less active (from the air phase to the liquid phase). The sum total of tamellar bodys, tubular myelin figures and multilametlated vesicles per alveolus was more significantly increased under the collapse or expiration of alveoli than under the inspiration (P(O. 01). ~ Under the state of collapse ofalveoli, the sum total of lamellar bodys, tubular myelin figures and multilamellated vesicles per alveolus in the asthmatic group was smaller than in the normal group(P(O.Ol). There were abnormal structures of PS in the asthmatic group, and alveolar macrophages were easily seen in the alveolar cavity, whose phagocytotic vesicles contained the remnants of PS. ~ By double staining with osmium tetroxide and RR, the alveolar lining layer consisted of a floccular layer of high electron density which was not distinguished the surface active film from its subphase. There existed the same structures on the surfaces of capillary endothelia or erythrocytes.[Conclusion! (l)Pulmonary surface active films were composed of multilayer molecules. When surface active films were contracted, the suoi total of PS structures of larger surfce activity was increased, and its number was reduced when expanded, which suggested that the conversion between PS structures of larger surfce activity and PS structures of smaller surface activity was mutual. (2) The number of PS structures of larger surfce activity was decreased and there were abnormal PS structures in the asthmatic group. (3) RR might reduce the effect of demonstrating the ultrastructure of PS.