Hypoxic-Ischemic Encephalopathy in Mice

I. The Distribution of Acute Brain Damage

Abstract

One-day-old mice, Jcl: ICR strain, were exposed to 5% oxygen for hours, 34% of animals survived and 59% of the surviving mice had intracranial hemorrhage. Intracranial hemorrhage could be detected without sacrifice of the animals: it could be seen through the thin skin and skull of the newborn mice. Surviving mice were sacrificed 6 hours after the exposure to hypoxia and their brains were examined pathologically.
Cortical hemorrhage usually appeared symmetrically in the bilateral parietal regions. In more affected cases it extended into the frontal and occipital regions. The distribution of such hemorrhagic lesions was similar to that of infarcted lesions of parasagittal cerebral injury in human neonates with hypoxic-ischemic encephalopathy. Hemorrhage and neuronal alternation were also found in deeper structures of the brain and the extent of cortical hemorrhage corresponded considerably to the severity of the whole brain damage. The pathogenesis of the cortical lesions was discussed.