Early axonal differentiation in mouse CNS delineated by an antibody recognizing extracted neurofilaments

A monoclonal antibody, C2, raised against chick embryo spinal cord, is shown by a solid phase immunoabsorbent assay to recognize a molecular species associated with neurofilaments extracted from adult mouse and rat brain. As immunoreactivity is lost following pre-treatment with alkaline phosphatase, the antibody probably recognizes a phosphorylated protein. Immunocytochemical staining in fetal mouse indicates that this antigen is expressed selectively in axons from the earliest stages of their development. Neuronal somata tend to show only weak immunoreactivity. The C2 antibody allowed visualization of the spatiotemporal pattern of axonal growth in the retina, neocortex and cerebellum with greater resolution than in previous light microscopic descriptions. The concept that the leading process of some classes of migratory neurons becomes transformed into an axon is supported by the expression of C2 immunoreactivity in radially ascending processes from principle neuron classes in the fetal retina and cerebellum.