Genetically determined defect of Schwann cell basement membrane in dystrophic mouse

Abstract

FOR more than a century there has been controversy as to whether Schwann cells are able to synthesise collagen and the collagen-related basement membrane^1,2. Recent evidence provides more direct proof that Schwann cells are indeed equipped to synthesise collagen and probably also a basement membrane in the same way as other cells of epithelial and neuroectodermal origin^3–5. Observations in various pathological situations, including regeneration after crush injury^6,7 and in peripheral nerve ischaemia⁸ indicate that axon regrowth and Schwann cell migration occur along scaffolding consisting of basement membranes and endoneurial collagen fibres. The role of the basement membrane and the endoneurial collagen in normal myelination has, however, remained largely unknown. It has been generally accepted that these extracellular elements provide not only mechanical support to peripheral nerves, but also that they are partly responsible for the relative lack of developmental faults in peripheral myelination⁹. A recent report¹⁰ suggests that the acquisition of a basement membrane by a Schwann cell occurs at the time that the cell establishes a permanent relationship with an axon. It is not known, however, whether the association of the axon with the Schwann cell induces the latter to synthesise basement membrane, or whether the Schwann cell only establishes a relationship with an axon once the Schwann cell has acquired a basement membrane.