Abstract
Technical improvements for the ultracytochemical demonstration of lining layer of the lung alveoli in adult rats are as follows: (1) Vascular perfusion of a twice diluted Karnovsky's fixative was applied to the lung tissues after air instillation into the airways, and minute tissue blocks were prepared by quick freezing and trimming of the prefixed lung. (2) Enzymic digestive method using a purified phospholipase C was performed in the floating prefixed minute tissues. After postfixation in cold osmium buffer, acetone was used for dehydration of the digested blocks to preserve phospholipids. (3) Ultracytochemical procedure using ruthenium red for mucopolysaccharides was carried out in the similarly treated minute lung blocks, and wire-meshed small cages were utilized as carriers to prevent floating throughout these procedures. Reaction products after phospholipase-digestive method, probably indicating the site of phospholipids, are clearly demonstrated on the surface film of the alveolar lining layers. Ruthenium red is abundantly visible in whole zones of acellular lining layer of the lung alveoli.
