To elucidate the early histopathological changes after transient focal cerebral ischemia, we made 1 h intraluminal occlusion of the middle cerebral artery on rats. After different reperfusion time, from minutes to 3 days, argyrophil III method was used for the demonstration of 'collapsed' (argyrophilic, dark) neurons. We could demonstrate the appearance of collapsed neurons in the lateral striatum and adjacent cortex where the dark neuron groups gave columnar patterns. These structures represent the ischemic core in this model. The collapsed neurons were detected also in the reticular thalamic nucleus, amygdala and hippocampus that are distant from the ischemic core. Data show that the early neuronal changes, demonstrated by this silver staining method, have a characteristic appearance in this model and involve more brain areas than were previously thought. These results could open more insight into the early pathophysiological processes triggered by the transient focal cerebral ischemia.
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