Light micrograph of pulmonary oedema. The alveolar spaces in this lung are filled with light pink oedema fluid. The irregular pink lines are the alveolar septa which form the boundaries between individual alveolar spaces. There are also some red blood cells (bright red dots) in the alveolar spaces. Haematoxylin and eosin stained tissue section. Magnification: 100x when printed at 10cm.