Neuronal Cu/Zn SOD immunoreactivity in intact immature brain. Widespread immunoreactivity for Cu/Zn SOD was observed mainly in neurons, both in the cytoplasm and nucleus, sparing the nucleolus. In the cortex, the highest expression was observed in cortical pyramidal neurons of layers V and III and II (A, B: Parietal cortex). In addition, the hippocampal pyramidal layer (CA1; C), and of substantia nigra (D) also displayed immunoreactivity. Scale bars: 50 μm in A and B; 20 μm in C and D.