[Morphological investigation of the neonatal lung with respiratory distress syndrome which was maximally distended with Somentor 33 and formalin (author's transl)].

The importance of morphological immaturity of the lung in the development of the respiratory distress syndrome was investigated. Atelectatic lungs of newborns were maximally expanded with a mineral oil of low kinematic viscosity (Somentor 33) or 10% Formalin. With this method, surface active forces of peripheral air spaces should not impede expansion of the lungs. 27 lungs of neonates who died of respiratory distress syndrome and 10 lungs of neonates without primary respiratory problems were examined. Following maximal expansion of the lungs with the respiratory distress syndrome show a hypercellular densely cellular tissue of the pulmonary segments, much like glanduloid hyperplasia with small peripheral air spaces and long distances for diffusion of the respiratory gases. The lungs of newborns without respiratory distress syndromes are well alveolar following expansion and show an optimal morphology for gas diffusion. A lack of a surfactant should have significant consequences in small air spaces.