[The appearance of surface-active phospholipids of the surfactant-system of the lung during ontogenetic development of humans (author's transl)].

In order to characterize the pulmonary maturity during ontogenetic development the following parameters were determined in the lungs of 30 fetuses respectively newborns with a weight between 15 and 4450 g: Water content (WC), total phospholipid content (TPC), lecithin concentration (LC), sphingomyelin concentration (SPC) and surface activity (SA) of the extracts. The water content decreases with increasing gestation age. The total phospholipid content and the lecithin concentration increase during the ontogenetic development. The sphingomyelin concentration remains approximately constant during lung development. No significant correlation exists between phospholipid content and surface activity. A relatively high TPC and a high SA was found in a 43 g-fetus (about 14th week of gestation). This result suggests, that the surfactant-system of the lung is produced earlier than supposed till now. Lungs of infants who developed respiratory distress syndrome (RDS) have a low concentration of TPC. The lecithin/sphingomyelin-ratio rises as gestation progresses. Lungs of RDS-children have - similarly in amniotic fluid - a low lecithin/sphingomyelin-ratio.