The oligodendrocytic junctional complex

Summary The junctional complex of oligodendrocytes was studied by means of different electron microscopical techniques. This complex is composed of the following junctional membrane formations: 1) tight Junctional domains in the oligodendrocytic membrane near the soma of the cells, 2) fasciae occludentes or focal tight junctions on the outer oligodendrocytic loop of myelin and on the outermost myelin membrane, 3) gap junctions of considerable size variations, either on membranes near the soma or on peripheral oligodendrocytic processes, and 4) non-paranodal transverse bands. The different types of oligodendrocytic junctions are discussed in terms of their functional implications.Supported by a grant from the Deutsche Forschungsgemeinschaft (SFB 114 Bionach) to R. DermietzelThe authors are indebted to Mrs. P. Kalweit and Mr. R. Eichner for technical assistance and Mr. A. Stapper for preparing the drawing. We also thank Mr. U. Malewski and Mr. Khing for their help with the English translation