Histological preservation and ultrastructure of alveolar surfactant.

We have discussed the three-dimensional structure of lamellar bodies as visible intracellular storage sites of surfactant. Among the intraalveolar structures, tubular myelin, a liquid crystal, represents a large aggregate of surfactant lipids and proteins of still-unclear significance. Elaborate fixation methods permit visualization in situ of localized pools of fluid that sometimes extend laterally, covering small areas of the alveolar surface.