Abstract: Objective To observed the pathological changes of closed diffuse brain injury in the rats died immediately and 15min to 5days after the injury. Methods H.E. staind and esterification－ silver stain were applied to investigate the closed diffuse brain injury.Results In rats died immediately after the concussive injury,a number of shrunken neurons(type I change),distended neurons(type II change)and wave－ like nerve fibers were identified in the brain tissue,especially in brain－ stem.At 2h and 8h after injury,brain edema and axonal swelling appeared clearly in the cortex and white matter,especially in brain－ stem.At post－ traumatic 8h and 24h,the axonal retraction balls began to appear.The amount of neurons undergoing type I and II changes and constraction balls increased along with the survivor time.After 4 days and 5 days,brain edema alleviated,but the retraction balls and axonal swelling still existed.With Esterifica－ tion silver stain,the above changes of neurons and nerve fibers were more obvious.With ABC stain,the distribution of albumin(Al) was extended from the perio－ vascular area to diffuse distribution.Al positive staining were more obvious in injuried neurons and nerve fibers.Conclusion The distribution of the concussive damage in the brain are coup,contra－ coup and centripental. [

Key words: closed diffuse brain injury, pathological changes, biomechanics