Infarct volume estimates. All eleven SHRs had infarct changes in the right hemisphere after 90 minutes of tMCAo, but three out of 13 SDs had no histological signs of infarct on the NeuN-stain. The infarct volume differed significantly between the two strains with a mean of 89.2 mm3 for the SHRs and 16.9 mm3 for the SDs (p < 0.005). The subcortical portion of the total infarct was 40.4 mm3 for the SHRs compared with 16.2 mm3 for the SDs (p < 0.044). The mean neocortical infarct volume was determined as the difference between the total infarct volume and the subcortical portion of the infarct. In eight out of eleven SHRs, we found neocortical involvement in the infarct as opposed to one animal out of 13 SDs. This reflects our general experience that SDs hardly get neocortical infarcts after 90 minutes of tMCAo. SDs are marked with "black squares", whereas "black circles" represent SHRs. Animals which did not have infarcts were marked with "black crosses" if they belonged to the SD strain or "black stars" if it were SHRs. Mean infarct volumes are marked with horizontal lines. * indicates p < 0.05, whereas p < 0.01 are marked with #. NeuN, neuronal nuclei; SDs, Sprague-Dawley rats; SHRs, spontaneously hypertensive rats.