Fig. 4. Higher-powered views of activated caspase-3-stained neurons in layer IV of the sensory cortex in neonatal mouse brain after exposure to 25% oxygen for 3 h or 6 h. Black dots represent caspase-3+cells. Note that relatively well-preserved activated caspase-3+neurons are occasionally observed (arrows ). These neurons may be in an early stage of degeneration. Representative images from one of eight mice per group. Scale bars: 50 μm. Cont = control; Des = desflurane; Iso = isoflurane; Sevo = sevoflurane.