Successful silver impregnation of degenerating axons after long survivals in the human brain.

Degenerating axons in the human brain were successfully impregnated with reduced silver methods. The appearance of degenerating fibers did not differ markedly with survival times of three weeks and two, six, and twelve years following cerebral infarction or contusion of the brain. Impregnated fibers were found only along the appropriate corticofugal pathways. Electron microscopic examination of Vibratome-cut, silver-stained sections demonstrated silver deposition almost exclusively within axon fragments. Previous studies using anterograde degeneration methods in the human brain have limited their choice of cases to those with short periods of survival. Relaxing the restriction of short survival times extends the range of cases which can be used to study neural connections which may be unique to, or different in, the human brain.