Neuronal injury following permanent middle cerebral artery occlusion in cats.

The border of a chronic infarct is sharply demarcated. We found in our investigation, however, that this is merely a macroscopic diagnosis and does not say anything about the structure of the tissue and the content of morphologically preserved neurons in the marginal zones. In six cats the left cerebral artery was permanently occluded. Eight weeks later the animals were killed and autoradiographic investigations were conducted on cryostat sections to determine rCBF. Adjacent to every 20-microns section, a 10-microns HE section was prepared. Preserved nerve cells were counted in several areas of the cortex in a symmetric fashion in both the infarcted and the contralateral side in the identical regions where rCBF had been measured in the preceding section. Two additional non-ischemic cat brains served as controls, which were investigated in the same manner as described above. A marked loss of neurons was observed in the border zone of the infarct. Only occasionally preserved ganglion cells were seen in each cortical layer. Even in areas one gyrus distant to the margin of the infarct the number of neurons was still reduced by one third as compared to the contralateral side. Starting only with the lateral gyrus the number of ganglionic cells was found to be equal on both sides.