Pulmonary surfactant is produced by Type II alveolar cells, and breaks the surface tension of the air-water interface of the alveoli. Surfactant is made up of choline-based lipids and proteins that are packaged into hydrophobic lamellar granules before they are secreted.
Fixed A549 cells on glass; wide-field, 60x (1.42 NA; oil)
Actin (green; cytoskeleton component, stained with AF488-phalloidin)
Nile Red (red; hydrophobic lamellar body vesicles)
DAPI (blue; nucleus)