For a long time neurons have blinded neuroscientists with their dazzling array of impulses and synapses. In thrall to these complex neural networks neuroscientists have often concentrated almost exclusively on neurons while the role of the macroglia – the oligodendrocytes and astrocytes – has remained in the shadows. We hope that this book will present a more integrated view of the relationship between oligodendrocytes and neurons and the critical role both cell types play in the central nervous system (CNS).

We aim to set out major aspects of the biology of the oligodendrocyte – a very large, very complex and dynamic cell – highlighting its extraordinarily unique organization and its multiple functions. For example, each oligodendrocyte can produce a plethora of up to 50 elongated paddle-like processes, each of which spirals around an internode of a different CNS axon. This spiraling process forms the compacted myelin lamellae and the associated uncompacted inner mesaxon, lateral paranodal regions and the outer mesaxons so often overlooked. The metabolic requirements and maintenance of such an elaborate organization of membranes depend on the uncompacted and compacted myelin compartments remaining in continuity. This continuity is achieved via the transverse processes and Schmidt–Lanterman incisures and ensures that vital cytoplasmic components have access to the compact myelin membranes. The orchestration of oligodendrocyte interaction with the neurons and other CNS cells is dependent on the precision of developmental processes including cell division, differentiation and migration to exact locations.