Ultracytochemical Studies on Lining Layer of Lung Alveoli

Abstract

Technical improvement described by the author for the investigation of pulmonary surfactant system in adult rats are as follows; ( 1 ) Vascular perfusion of dilute Karnovsky's fixative was used for the lung tissues after air instillation into their airways. ( 2 ) Minute tissue blocks were prepared by quick freezing and trimming of the prefixed lungs. (3) Phospholipase-digestive method using a purified phospholipase A₂ or C was performed in the floating prefixed minute blocks. (4)After postfixation in 2% osmium buffer, acetone was used for dehydration of the digested minute blocks to preserve phospholipids. In addition, Dermer's technique for saturated phospholipids and the ultracytochemical procedure using ruthenium red for mucopolysaccharides were also performed, in which wire-meshed cagos were utilized as carriers of the minute lung tissues to prevent the floating.
Saturated phospholipids were clearly demonstrated on the surface film of the alveolar lining layers. In addition, positivity for phospholipids could be detected in a few myelin figures in Type 2 alveolar epithelial cells and the alveolar cavities. Mucopolysaccharides were observed in the whole acellular lining layers of the lung alveoli.