Endogenous peroxidatic activity in the cerebral and cerebellar cortex of normal adult rats

There are at least three sources of endogenous peroxidatic activity that are present in both the cerebral and the cerebellar cortex. All three sources, being neuronal, astrocytic or hemoglobin-dependent, may obscure the interpretation of studies using exogenous horseradish peroxidase. The activities are to a variable extent influenced by fixation. From the present results DAB-incubation of cryostate sectioned brain appears to be an acceptable method for histochemical demonstration of the mitochondrial cytochrome chain enzymes.