Figure 5: Comparison of histopathology in rat lungs 24 h post injury in various experimental groups. (Magnification: x100; haematoxylin and eosin staining). (a) LPS group: The alveolar epithelium was severely damaged. Large volumes of exudates containing neutrophils and lymphocytes (arrow) were found in the alveolar cavity. (b) OA group: Pulmonary congestion, oedema and haemorrhage (arrow) are apparent. The lung tissue was infiltrated with lymphocytes. (c) LPS and OA combination group: The lungs showed severe degree congestion, oedema and infiltration with inflammatory cells. The alveolar cavity contained remarkable amount of inflammatory exudates and protein fluid (arrow). The entire lung was filled with plasma – like fluid, suggesting severe injury to alveoli. (d) Control group: Histopathology of rat lungs in control group. The alveolar walls were very thin and the majority of the alveoli contained no cells demonstrating normal architecture of lungs. Two different arrows are pointing towards (1) thin alveolar walls in the lungs (thick arrow) and (2) bronchioles (thin arrow).