Further studies of the role of surfactant in premature rupture of the membranes.

Abstract

The purpose of this study was to assess the hypothesis that surface-active phospholipid (i.e., amniotic surfactant) plays a major role in maintaining the mechanical integrity of the chorioamniotic sac. Three studies were designed using chorioamniotic sacs from normal term deliveries. First, it was demonstrated how the extreme hydrophobicity (and lubricity) of amniotic and chorionic epithelium could be greatly reduced by incubating the membrane with bile salts, which react with surface-active phospholipid. Second, hydrophobic probes were used under epifluorescence microscopy to identify any structured surface-active phospholipid. Third, electron microscopy was used to investigate the ultrastructure, by means of a novel fixation procedure that does not destroy hydrophobic interfaces. Both morphologic studies confirmed planar structures of oligolamellar surface-active phospholipid running parallel to the membrane that contained lamellar bodies. These sheets of surface-active phospholipid could be very cohesive within the planes, thus improving tensile strength while promoting shearing between planes to provide the type of lubrication afforded by graphite whose ultrastructure they closely resemble.