Schwann cell precursors: Where they come from and where they go

Abstract

Schwann cell precursors (SCPs) are a transient population in the embryo, closely associated with nerves along which they migrate into the periphery of the body. Long considered to be progenitors that only form Schwann cells-the myelinating cells of nerves, current evidence suggests that SCPs have much broader developmental potential. Indeed, different cell marking techniques employed over the past 20 years have identified multiple novel SCP derivatives throughout the body. It is now clear that SCPs represent a multipotent progenitor population, which also display a level of plasticity in response to injury. Moreover, they originate from multiple origins in the embryo and may reflect several distinct subpopulations in terms of molecular identity and fate. Here we review SCP origins, derivatives and plasticity in development, growth and repair.

Keywords: Cell lineage; Neural crest; Peripheral nervous system; Schwann cell precursor.

Figure 1:. Embryonic origins of Schwann cell precursors.

Transverse cross-section through the neural tube showing three pathways giving rise to Schwann cell precursors (orange) that have been discussed in the literature: 1. Neural crest cells (blue) migrate from the dorsal neural tube and give rise to Schwann cell precursors along the dorsal root along which they migrate into the periphery. 2. Neural crest cells (blue) migrate to the site of the future dorsal root entry zone (DREZ) or future motor exit point (MEP) where they give rise to boundary cap cells (green). These boundary cap cells then give rise to Schwann cell precursors along the dorsal and ventral roots. 3. The neuroepithelium (purple) is a currently contested source of Schwann cell precursors along the ventral and possibly dorsal roots. Arrows show direction of migration.

Figure 2:. Schwann cell precursor derivatives.

Schwann cell precursors (orange) have been shown to give rise to a diverse range of cell types (blue). Grey circles represent axons, viewed in transverse cross-section. Arrows show direction of differentiation.