Immunohistochemical localization of neurofilament antigen in rat cerebellum

The distribution of neurofilaments in the rat cerebellar cortex was studied by immunoperoxidase histochemistry using an antiserum raised against neurofilaments isolated from brain (anti-NF). In light microscope preparations, this antiserum selectively stained known neurofilament-containing structures. Staining was most intense in myelinated axons of the white matter and in the terminal branches of basket cell axons. No staining was apparent in either neuronal or glial cell bodies or in glial cell processes. These findings were confirmed in electron microscopic preparations of the same material. Neurofilaments stained by the antiserum were abundant in basket cell axons and also occurred in small bundles in mossy fibre terminals. Adjacent microtubules were not stained by the antiserum. There was no evidence of stained cytoplasmic filaments in glial cell processes. Thus it appears that neurofilaments contain unique antigens which do not occur in either microtubules or in glial cytoplasmic filaments. The antiserum did not induce staining of synaptic junctional structures, a result which contradicts previous suggestions that neurofilaments are structural components of synaptic densities.