Temporary [corrected] cerebral ischemia results in swollen astrocytic end-feet that compress microvessels and lead to delayed [corrected] focal cortical infarction.
We examined the mechanisms underlying the abrupt onset of the focal infarction in disseminated selective neuronal necrosis (DSNN) after temporary ischemia. Stroke-positive animals were selected according to their stroke-index score during the first 10 minutes after left carotid occlusion performed twice at a 5-hour interval. The animals were euthanized at various times after the second ischemia. Light- and electron-microscopical studies were performed chronologically on the coronal-cut surface of the cerebral cortex at the chiasmatic level, where focal infarction evolved in the maturing DSNN. We counted the number of neurons, astrocytes, and astrocytic processes (APs); measured the areas of end-feet and astrocytes; and counted the numbers of obstructed microvessels and carbon-black-suspension-perfused microvessels (CBSPm). Between 0.5 and 5 hours after ischemia, DSNN matured, with the numbers of degenerated and dead neurons increasing, and those of APs cut-ends decreasing; whereas the area of the end-feet and the numbers of obstructed microvessels increased and those of CBSPm decreased. At 12 and 24 hours after ischemia, the infarction evolved, with the area of end-feet and astrocytic number decreased; whereas the numbers of obstructed microvessels decreased and the CBSPm number increased. The focal infarction evolved by temporary microvascular obstruction because of compression by swollen end-feet.
Ito
Umeo
U
Department of Neuropathology, Tokyo Metropolitan Institute for Neuroscience, Tokyo, Japan. umeo-ito@nn.iij4u.or.jp
Hakamata
Yoji
Y
Kawakami
Emiko
E
Oyanagi
Kiyomitsu
K
D000818:Animals; D001253:Astrocytes / Q000473:pathology* / Q000648:ultrastructure; D002196:Capillaries / Q000473:pathology* / Q000648:ultrastructure; D002452:Cell Count; D016923:Cell Death; D048429:Cell Size; D002544:Cerebral Infarction / Q000473:pathology*; D003593:Cytoplasm / Q000473:pathology / Q000648:ultrastructure; D005849:Gerbillinae; D002546:Ischemic Attack, Transient / Q000473:pathology*; D008297:Male; D008854:Microscopy, Electron; D008928:Mitochondria / Q000473:pathology / Q000648:ultrastructure; D009336:Necrosis / Q000473:pathology; D009410:Nerve Degeneration / Q000473:pathology; D009474:Neurons / Q000473:pathology / Q000648:ultrastructure