Cytologic changes in neurons of the neocortex of mice consequent to suboptimal fixation have been investigated systematically in Golgi-rapid preparations. With few exceptions, there is no alteration in cellular morphology if the brain is refrigerated after death, and fixed by immersion within 3 hours. With latencies of fixation of 6 hours or more, autolytic changes supervene which modify the general histologic appearance and the morphology of individual cells. In general, the degree of tissue and cellular change is proportional to the latency between death and tissue fixation. Similar alterations in cellular morphology and general tissue appearance are found in Golgi-rapid impregnations of human brains obtained at autopsy. However, the degree of tissue autolysis in the human specimens bears a less predictable relationship to the latency of fixation after death. The duration of preterminal metabolic encephalopathy appears to be equally decisive as a determinant of tissue preservation.
Adolescent Adult