Excitotoxicity in the spinal cord explant cultures. A) A spinal cord culture was stained for expression of the neuronal marker MAP-2 (Blue) and for the oligodendrocyte marker oligodendrocyte-specific protein (OSP) (Red). One hemisphere is boxed to show the regions from other slices which appear in panels B and C (bar = 400 μm). Hemispheres of a slice cultures stained for MAP-2,(Blue), OSP (Red) and activated caspase 3 (green) are shown for untreated (B) control and kainic acid (KA) (C). (Magnifications are 2× for A and 4× for B and C, bar = 80 μm for B, C and = 20 for D μm). (D). A higher magnification (60×) of the white matter region showing oligodendrocytes stained for CNPase (red) and activated caspase 3 (green) and co-labeling with both as yellow. Examples of oligodendrocytes containing activated caspase 3 are shown (see white arrows). An example of a cell labeled for activated caspase 3 which is not an oligodendrocyte (and likely a motor neuron) is shown with a gray arrow.