Hematoxylin and eosin examination under light microscopy. A &B, Normal rat lung showing thin interstitial alveolar wall and fine capillary vessels. Rare inflammatory cells in the wall and intra-alveolar spaces are noted and minimal swelling around blood vessels. C &D After five days of hyperoxia, thickening of the interstitial wall, capillary congestion and the inflammation is noted. At higher magnification, neutrophil and the increased mononuclear inflammatory cells within the wall and the alveolar spaces are observed. E &F: With PJ supplementation, a significant reduction in the thickness of the interstitial alveolar wall and the marked reduction in the number of inflammatory cells is noted. There is now resemblance to normal tissue in A &B.