Abstract: To set up the experimental model of focal cerebral contusions in rats,and to study the histology and the expression of Bax and Bcl－ 2 after cerebral catusions.It was found that neurons and astrocytes around the wound area were changed morphologically and that polymorphonuclear leucocytes were present at 12－ 24h after injury. A lot of foamy cells and astrocytes having a big dark nucleus appeared around the wound area on the 4th day after injury. On the 8－ 10th day, liquefaction necrosis was seen in areas of contusions. On the 12－ 14th day, the contusion focus healed up and became cystiform or glial node. Meantime, lots of astrocytes, capillary vessel and hemosiderin were observed. The expression of Bax and Bcl－ 2 increased after injury. There existed a relationship between increased Bax/Bcl－ 2 and different intervals after brain injury.

Key words: cerebral contusion, timing of injury, apoptosis, bax, bcl－ 2, immunohistochemistry, histology