[The distribution of actin on cultured oligodendrocytes from rat optic nerve].

Two types of cultured oligodendrocytes (OLs) from rat optic nerve were analyzed for the distribution of actin, a major contractile protein, using immunocytochemistry. Type 1 OLs showed extensive network of processes and type 2 OLs showed elaborate membranous expansion along an extensive network. Actin was diffusely stained on an extensive network of processes in type 1 OLs and on the distal portion of membranous expansion in type 2 OLs, but some oligodendrocytes were not stained. It was demonstrated that the distribution of actin in type 1 OLs and type 2 OLs varied with development in oligodendrocyte differentiation and maturation. Our results suggest that undifferentiated and immature oligodendrocytes display remarkable cell movement to search for target axons, and differentiated and mature oligodendrocytes do not require cell movement when myelination has finished. In conclusion, it is considered that actin plays an important role in myelinogenesis.

The isolation of cultured oligodendrocytes from rat optic nerve.

Oligodendrocytes, the myelin-forming cells of the central nervous system, were cultured from newborn rat optic nerve employing a modified method of McCarthy and DeVellis, and cultured oligodendrocytes were analyzed for characteristic morphology and maturation events by phase contrast, MBP immunofluorescent and scanning electron microscopy. Two types of oligodendrocytes, type 1 OLs and type 2 OLs, on poly-L-lysine-coated dishes were obtained. Type 1 OLs showed extensive networks of processes and type 2 OLs elaborated membranous expansion along extensive networks, and it was demonstrated that type 2 OLs developed from type 1 OLs by phase contrast-microscopic observation. By scanning electron-microscopic observation, membrane structure in type 2 OLs clearly corresponded to membranous expansion. Our results suggest that type 1 OLs and type 2 OLs are in the different states of the myelinogenesis, and that membranous expansion and membrane structure in type 2 OLs correspond to myelin membrane.

Monoclonal antibody RG1 against rat Müller cells recognizes optic nerve and cerebral cortex glia in culture.

A monoclonal antibody designated as RG1 was produced by the fusion of mouse myeloma cells with spleen cells from mice immunized with rat retinas. The monoclonal antibody was shown to bind to Müller cells of the rat retina by the avidin-biotin peroxidase complex method. The screening of antibody-producing hybridomas and the analysis of the monoclonal antibody obtained were performed by enzyme-linked immunosorbent assay. The optic nerve, cerebral cortex and dorsal root ganglia were cultured from 17-day embryonic rats and maintained for 17-20 days. Expressions of the RG1 antigen were examined by indirect immunofluorescence in the cultured glial cells. In both the optic nerve and the cerebral cortex glial cells the RG1 antigen was expressed; however, the RG1 antigen was not expressed in cultured Schwann cells throughout the whole culture period. Our results suggest that the RG1 antigen is a common antigen in the supporting neuroectodermal glial cells in the central nervous system.