In situ demonstration of mature oligodendrocytes and their processes: An immunocytochemical study with a new monoclonal antibody, Rip

This paper introduces “Rip” a monoclonal antibody that produces relatively complete staining of oligodendrocytes and their processes in the adult central nervous system (CNS). The distribution of Rip immunoreactivity coincides with that of myelinated axons in both the spinal cord and the cerebellum. In addition, doubleimmunolabeling experiments demonstrate that Rip stains processes containing myelin basic protein but does not stain processes that express glial fibrillary acidic protein. These results indicate that Rip selectively stains oligodendrocytes but not astrocytes. Moreover, individual Rip‐stained oligodendroglial somata and their cytoplasmic processes were observable at both the light microscopic and electron microscopic level when the staining of myelin was reduced. This was accomplished by omitting detergents from antibody incubation steps. Rip‐stained oligodendrocytes have multiple processes of varying thickness, some of which end in close proximity to myelin sheaths. These immunostained profiles, reminiscent of those observed in oligodendrocytes stained by Golgi methods, are unique to Rip and indicate that its immunoreactivity is distinct from that of existing serological markers for oligodendrocytes.