Cell-specific Cu/Zn SOD expression in the early excitotoxicaly lesioned immature brain. In the injection site, Cu/Zn SOD immunoreactivity decreased from 2–4 hours after the NMDA injection, and continued to be downregulated until 24 hours after injection (A-B,SPN: sub-plate neurons, V and II-III: cortical layers). Neurons from the injected cortex after 4 hours showed slightly condensed chromatin (compare C and D: arrows), and a shift of NeuN staining from the soma and nucleus towards the nucleus (compare F and G: arrows) in the absence of TUNEL staining (H). From 10 hours after lesion onward, neuronal nuclei showed clear apoptotic signals like condensation and blebbing (E: arrows) and TUNEL staining (I). Scale bars in A-B: 200 μm; in C-G 5 μm; and in I-H: 40 μm.