Effect of NBO on DNA fragmentation in cortex penumbra at 22.5 h reperfusion after 90-min ischemia. A) Representative photographs showing the effect of NBO on DNA fragmentation by TUNEL in cortex penumbra. Bar = 20 μm. B) TTC staining. The black square indicates where the photos were taken from. C) Numbers of TUNEL-positive cell in the cortex penumbra. Data is expressed as mean ± SD, n = 5 each group. *P < 0.05 and **P < 0.01 vs. normoxic control.