Light and electron microscopic studies of the pulmonary alveolar surfactant

22 methods of light and electron microscopy have been tested for the identification of the pulmonary alveolar surfactant. Among the non electron microscopic methods Romhányi's anisotropic staining with toluidine blue was the most serviceable. In addition to simple performance it allows the identification of the smallest alteration -- not to be identified by other methods -- of the alveolar surfactant. Among the electron microscopic technics Ruthenium Red staining and Dermer's tricomplex method yielded the best results. Given that different chemical components of the alveolar surfactant will be identified by these 2 methods they supplement each other favourably. In the study of human cadaver material Baker's phospholipid reaction and Romhányi's anisotropic toluidine blue reaction is being used.