Fig. 4

Representative images of lung histology of a 3-h murine experimental study where subjects were randomized to three groups: Group I: subjects with normal (uninjured lungs) on spontaneous breathing (no mechanical ventilation) (a, b). Group II: subjects with induced lung injury on low Vt mechanical ventilation (c, d). Group III: subjects with induced lung injury on spontaneous breathing (no mechanical ventilation) (f–j). In the first image set, no edema or perivascular infiltration is appreciated at ×100 (a) and ×200 (b). In the second image set, minimal amount of perivascular fluid is occasionally observed at ×100 (c–e). In the third image set, we observed alveolar wall disruption and hemorrhage at ×400 (f), perivascular edema and hemorrhage at ×200 (g), intense hyperemia in lung parenchyma vascular bed with signs of initial perivascular edema and leucocyte infiltration at ×200 (h), intense hyperemia and perivascular accumulation of leucocytes at ×100 (i), and perivascular accumulation of polymorphonuclear cell leucocytes and lymphoid cells at ×400 (j)