The apoptotic pneumocytes were observed in the segment distal the clot. A. There were no apoptotic cells detected on slides in Sham group. B. In the Ischemia group, the slides revealed some apoptotic pneumocytes shown by TUNEL (white arrow). C. In the Reperfusion group, the number of apoptotic pneumocytes was much more than Ischemia group (white arrow). D. In the Inhaled NO group, there were also many apoptotic pneumocytes (white arrow).