OUTSTATIONS OF THE GOLGI-COMPLEX ARE PRESENT IN THE PROCESSES OF CULTURED RAT OLIGODENDROCYTES

Primary cultures of rat oligodendrocytes were incubated with a fluores cent sphingolipid precursor, benz-2-oxa-1,3,-diazol-4-yl)amino]hexanoy lceramide (C-6-NBD-ceramide). This compound is known to stain the Golg i complex specifically. Within 30 min of incubation at 37 degrees C mo st of the C-6-NBD-ceramide was incorporated into the perinuclear Golgi system, as revealed by conventional and confocal laser fluorescence m icroscopy. Interestingly, C-6-NBD-ceramide was found to accumulate als o in smaller, oval-shaped structures in many of the processes, at dist ances up to 30 mu m from the nucleus. This implies the possibility tha t these structures are Golgi (-derived) complexes. Indeed, after incub ation of oligodendrocytes with C-6-NBD-ceramide and rhodamine-labeled transferrin both fluorescent labels colocalized in the Golgi system of the cell body as well as in the structures in the processes. Addition al support for the Golgi character of these structures was obtained by transmission electron microscopy. Particularly in oligodendrocytes co cultured with neurons, many Golgi structures were present all over the processes. The results lead us to conclude that, in the oligodendrocy te, the Golgi complex does not only reside in the perikaryon, but also in the processes. One can speculate that a polarized biosynthetic act ivity, involving the presence of the Golgi near the site of myelin syn thesis, may be advantageous to the oligodendrocyte for assembly and/or repair of the myelin membrane at the distal end of the processes. (C) 1993 Wiley-Liss, Inc.