Abstract: In order to observe dynamic change characters of the apoptosis happened in the local ischemic penumbra of rats,models of MCAO(middle cerebral artery obstruction)were made with the thread plugged method. A specific method to test apoptosis named TUNEL method was supplied to observe the ischemia involved brain tissue that happened at different time. Most of the marked positive cells, which were detected at different time, were noticed at local ischemic penumbra areas. The number of apoptosis cells were 3.60±1.02/mm², 15.60±2.06/mm², 22.40±1.85/mm², 33.00±2.83/mm² respectively which were calculated at 1,3,6,12 h after artery obstruction .It reached at 46.60±3.01/mm² 24 h after obstruction and reduced to 13.60±2.47/mm² 48 h later. It gradually disappeared (5.00± 1.41/mm²)after 72 h. The differences above were confirmed by the statistic analyses(P< 0.01).The number of apoptosis increased following the duration after ischemia of brains, it reached at peak value at 24 h later and reduced significantly after 48 h,then, it almost disappeared after 72 h of obstruction.

Key words: apoptosis, ischemic penumbra, MCAO