抄録
The ultrastructural localization of mucopolysaccharide in the pulmonary alveolus of a rat was studied by means of the colloidal iron reaction, the ruthenium red staining and the phosphotungstic acid (PTA) staining.
Colloidal iron-positive material was observed in a thin layer, 15-25nm in thickness, closely attached to the luminal surface of the alveolar epithelium. The superficial layer, the hypophase, and the tubular-myelin figures, however, lacked the colloidal iron reactivity. Ruthenium red-positive material was observed on the luminal surface of the alveolar epithelium as well as in the hypophase. In the ultrathin sections stained with PTA (pH 0.4 and 1.5), the microvillous surface of the type II cell was densely stained, whereas the luminal surface of the type I cell was not discernible. The results suggest that acid mucopolysaccharide is not involved in the surfactant lining, but may be in existence as a surface coat on the alveolar epithelium; the surface coat on the type II cell differs chemically from that on the type I cell.
