Representative images showing neurodegeneration in the CA1 region of the hippocampus following transient forebrain ischemia. (A~C) Double- labeling for the neuron-specific marker NeuN and the cell death marker terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) in the hippocampal CA1 region of sham-operated rats (A) and ischemic rats, 3 days after reperfusion (B and C). Note the lack of TUNEL-specific staining in the pyramidal cell layer of saline-treated controls, whereas most pyramidal neurons of the ischemic animals are positive for TUNEL (arrowheads). (D~F) Changes in immunoreactivity for microtubule-associated protein 2 (MAP2) in the CA1 hippocampus after ischemia. (D) In sham-operated rats, extensive labeling for MAP2 is noted in both somata and dendrites in the CA1 hippocampus. (E) Three days after reperfusion, loss of both somatic and dendritic labeling for MAP2 is evident in the CA1 hippocampus. (F) At 14 days, only a few remaining dendrites are noted in the CA1 hippocampus. Cell nuclei are stained with 4′,6-diamidino-2-phenylindole (DAPI). Scale bars represent 20 μm in A~F.