Studies on tubular myelin figures of lining layer of lung alveoli

Abstract

Extracellular alveolar lining layer of mammalian lungs is rich in phospholipids associated or bound to proteins and carbohydrates. There are implications that all the molecular components aggregate in an obligatory sequence and that protein has an organizing role. In electron microscopy alveolar lining layer is composed of a surface film and a liquid subphase. The latter is marked with tubular myelin figures /TMF/. In this report some attempts to characterize more precisely the TMF are presented.Prefixation of tissue samples in osmium or glutaraldehyde vapor was followed by fixation in diluted Kamovsky′ s fixative. The TMF is composed of lamellae showing the unit membrane structure. On cross section the TMF reveal a square lattice pattern. The centre of each square contains fragments of a somewhat circular profile /Fig. 1/, suggesting also their linear continuity along the axis of each tubule. The tridimensional reconstruction reveals that the fragments may belong to a randomly coiled formation located in the centre of tubule.