Recirculation in Ischemic Focus in the Acute Stage

Histological changes in the ischemic focus after recirculation were examined by electron microscopy, using a thalamic infarction model in the dog. In this model, the regional blood flow in the ischemic focus decreased to 10 ml100 gmin, about 13 of the pre-occlusion value, after occlusion of the intracranial arteries. Mild swelling of the endoplasmic reticulum and mitochondria and dispersion of polysomal rosettes were found after a 30 minute occlusion. Recovery from these changes occurred after 12 or 24 hours of recirculation. Spongiosis of neuropil and slight swelling of the perivascular glial endfeet also recovered. On the other hand, severe swelling of the endoplasmic reticulum and mitochondria, with destroyed crista and severe shrinkage of the cytoplasm of the nerve cells were found after 1 or 2 hour occlusions. After recirculation, disruption of nerve cells and glial cells are frequently found in the ischemic focus. In this thalamic infarction model, therefore recirculation after 30 minutes was effective for recovery, but recirculation after 1 or 2 hour occlusions was not effective, on the contrary, tissue damage was aggravated.