It is now over 200 years since Theodore Schwann first described the cell which bears his name. Such early descriptions of nervous system components were done without the powerful microscopes we have today, yet Schwann and Ramon Y. Cajal made foundation observations which still stand. Cajal's papers, especially, show the power of careful observation, an essential element of good science.
The Schwann cell has been historically underrated and poorly understood. In particular, the myelin-forming Schwann cells or their myelin are still often referred to as a simple ‘sheath’ for the neuron. However, Schwann cells in all their complexity form essential partnerships with neurons, and muscles. This is of particular relevance in the case of the myelin-forming Schwann cell, an enormous cell that expresses unique molecules and complex relationships related to maintenance of the compact and non-compact myelin regions of its plasma membrane. Schwann cells have other complex interactions, not least of which are found where nerve terminals and muscle fibres form the tripartite synapse in association with the perisynaptic Schwann cells. There are also the poorly understood satellite cells that surround the dorsal root ganglion nerve cell bodies, and of course the complexity of non-myelinated Schwann cells and their axonal associations.
It may be that the histopathological prominence of abnormalities of compact myelin has focussed research on this region of the Schwann cell.