Improvements in demonstration of lining layer of lung alveoli by electron microscopy

Improvements in the technique for lung fixation by vascular perfusion have resulted in a better preservation of a duplex lining layer of alveoli. This method is exposed in detail; technical difficulties and the significance of artifacts are discussed. The structural features of this layer, as well as its derived composition, strongly support the notion that this lining layer represents the surfactant lining of pulmonary alveoli. The question whether this layer is artificially produced in the sense of edema formation is experimentally studied and denied. The possible relationship between morphological features and chemical composition is discussed. An attempt is made to explain the observed distribution of the layer.