RAT-BRAIN OLIGODENDROCYTES DO NOT INTERACT SELECTIVELY WITH AXONS EXPRESSING DIFFERENT CALCIUM-BINDING PROTEINS

A single oligodendrocyte may endow ten to twenty vicinal axons with in ternodal segments, but its radial domain is neither exclusive of proce sses from other like cells nor are all nerve fibres within this zone m yelinated. Whether oligodendrocytes are able to discriminate between a xons on the basis of chemical or electrophysiological differences, or whether the tactic response is random, has yet to be established. In o rder to shed some light on this process, we investigated the ensheathm ent, by single oligodendrocytes, of axons distinguished on the basis o f their calcium-binding protein complexion. Rat brain oligodendrocytes were visualized either with the Rip-antibody or by intracellular inje ction of Lucifer Yellow; subclasses of axons were immunolabelled with antibodies against one of the two calcium-binding proteins parvalbumin or calretinin. Individual oligodendrocytes did not exhibit exclusivit y with respect to their preferment for axons containing calcium-bindin g proteins, associations with both non-immunoreactive, as well as with parvalbumin- or calretinin-positive ones, being encountered. (C) 1996 Wiley-Liss, Inc.