Early ultrastructural changes in the cerebral cortex of rat during ischemia.

The conducted investigation of the cerebral cortex of the rat during different survival periods following reduction in the cerebral circulation demonstrated an early occurence of ischemic changes characterized by different states of nerve and glial cells. The largest group was made up of neurons of deeper layers exhibiting reactive state of the nucleus and nucleolus and signs of chromatolysis in the cytoplasm. A less common pathology was represented by "dark" type changes observed in small stellate and pyramidal neurons of superficial layers. Changes of glial units manifested mainly as swelling and partial melting. The changes observed in neurons are indicative of variability of neurons of superficial and deep layers in sensitivity as well as of different mechanisms underlying structural regulation of cell metabolism and ensuring its optimum level and organization for each functional state.