FIG 4. Electron micrographs of neurons (original magnification x3000) and astrocytes (original magnification x4500).

A and B, At the end of 30 minutes of ischemia. A, Shrunken neurons (N) with condensed nuclei and cytoplasm are surrounded by a ring of swollen astrocytic processes (a). B, Swollen astrocyte with clumps of heterochromatin around the edge of its nucleus and an abnormally wide rim of watery perikaryal cytoplasm, which contained a few swollen mitochondria (m).

C and D, At the end of 90 minutes of reperfusion. C, Two markedly shrunken neurons with highly condensed nuclei and cytoplasm; these neurons are surrounded by severely swollen astrocytic processes (a). D, Greatly swollen astrocyte with extensive and watery perikaryal cytoplasm and a few contracted mitochondria (m).

E and F, At the end of 12 hours of reperfusion. E, Two necrotic neurons show cytoplasmic and nuclear disintegration with marked chromatin clumping and discontinuous cellular membranes. F, An irreversibly injured astrocyte with breaks in the nuclear membrane (arrows), watery cytoplasm, and severely swollen mitochondria (M).