Features and functions of oligodendrocytes and myelin proteins of lower vertebrate species.

The myelin-forming cells in the central nervous system (CNS) of lower vertebrate species, in particular those of fish, profoundly differ from their mammalian counterparts in their biochemical phenotype in that they express Po-like glycoproteins as major myelin protein constituents instead of proteolipid protein, while in their overall cellular structure and their cell lineage relationships, they closely resemble mammalian oligodendrocytes. While molecular biology in the past has allowed to appropriately classify the major myelin proteins synthesized by fish oligodendrocytes, heterologous expression studies are expected to give a deeper insight into the particular features and the conserved functions of these proteins required for myelin formation and maintenance in fish. It is hoped that this approach will also help to improve our understanding of the molecular processes underlying the unique capacity of fish oligodendrocytes for remyelination after injury in the CNS. This survey may stimulate neuroscientists to engage into this exciting field.