Figure 4.

Macro- and microscopic appearance of lung tissue and cytokine levels. A, Gross appearance of the lungs is shown while being ventilated ex vivo with peak inspiratory pressures of 20 cm H₂O. Compared with the well-inflated lungs of the surfactant-treated animals, the control lungs are collapsed with patchy hemorrhage. B, The wet-to-dry weight ratio was lower in Surfactant group than Control group. Representative lung histology in control (C–E) and surfactant-treated animals (F, G). C, Hemorrhage, (D) septal thickening, hyaline membranes (arrowheads), (E) neutrophilic inflammation and proteinaceous exudate (asterisk) were more prominent in the control lungs; vascular thrombi (D, inset) and multinucleated giant cells (E, inset) were occasionally seen. The alveolar architecture was generally well preserved in the surfactant-treated group with less inflammation and thin alveolar walls (F and G). H, The Lung Injury Score was lower in surfactant-treated than control animals. Values are means ± sem. ^*p < 0.05.