Electron microscopy of lung parenchyma. Animals were randomly assigned to hypovolemia (HYPO), normovolemia (NORMO) or hypervolemia (HYPER) with recruitment maneuver (RM-CPAP) or not (NR). Type II pneumocyte (PII) as well as alveolar capillary membrane were damaged in all acute lung injury groups. Note that the alveolar-capillary membrane is less damaged in the HYPO-RM-CPAP group (ellipse) compared with the other groups. In NORMO-RM-CPAP, there was a detachment of alveolar capillary membrane (arrow). In HYPER-RM-CPAP, note that alveolar compartmentalization is lost with disorganization of the alveolar cellular components. Photomicrographs are representative of data obtained from lung sections derived from six animals. EN, endothelial cell.