Selective necrosis and total necrosis in focal cerebral ischemia. Neuropathologic observations on experimental middle cerebral artery occlusion in the macaque monkey.

Temporary (15 minutes to 24 hours) or permanent focal cerebral ischemia was induced in 87 awake monkeys (Macaca mulatta and Macaca fasicularis) by transorbital snare ligation of the middle cerebral artery (MCA) and neuropathological evaluation was carried out two weeks later. The size, location and histology of lesions varied within each time-period of MCA occlusion. However, most animals that underwent long-term ischemia (eight hours to permanent) had a single, confluent infarct involving deep and sometimes cortical structures. These animals had total necrosis chracterized by: 1. indiscriminate involvement of white and gray matter, 2. relatively sharp margins containing astrocytic and mononuclear cells, 3. an inner zone of liquefaction, infiltrated with fat-laden macrophages and newly formed blood vessels. Animals that underwent moderate to short-term ischemia (30 minutes to four hours) showed multiple, non-confluent deep infarcts. These animals had selective necrosis characterized by: 1. involvement of gray matter and relative sparing of white matter, 2. poorly circumscribed, multiple and often perivascular lesions with incomplete tissue destruction, 3. preferential loss of neurons and proliferation of reactive astrocytes and microglia.