FIXATION OF PULMONARY SURFACTANT FOR ELECTRON MICROSCOPY .I. ALVEOLAR SURFACE LINING LAYER

The epithelial surface of the lung is thought to be lined by a layer of surface-active (surfactant) material. To date, however, there has not been a convincing morphologic demonstration of such an alveolar surface lining layer. Both the major and surface-active component of this material is a saturated phospholipid-dipalmitoyl lecithin. Since standard electron microscopic fixation techniques cannot be used to fix fully saturated lipids, a tissue fixation scheme has been developed which is effective regardless of whether the phospholipids are saturated or unsaturated. This technique (tricomplex flocculation by means of suitable ions) has permitted the electron microscopic visualization of the phospholipid component of surfactant within lung tissue. After tricomplex fixation, a layer of electron dense, polymorphic material is seen lining the epithelial surfaces of alveoli. © 1969 Academic Press, Inc.