Chapter 39 - Signaling pathways that regulate glial development and early migration—Schwann cells

Abstract

This chapter describes the development of peripheral glial cells in embryonic and early neonatal nerves of rodents. It examines in detail the origin of Schwann cells and the cellular transformations that lead to the appearance of immature Schwann cells, the glial cells in rodent nerves at birth, and discusses the molecular signals involved. There are three main transitions in the lineage. First, the formation of Schwann cell precursors when neural crest cells enter nascent nerves and form intimate relationships with axons, a step that involves significant changes in the expression of hundreds of genes. Like early central nervous system glia, these cells retain developmental multipotency. Second, the precursor-to-immature Schwann cell transition, which is characterized by the appearance of additional differentiation markers, as well as autocrine survival circuits, formation of endoneurial connective tissue and basal lamina. Finally, in peri-and postnatal nerves, immature Schwann cells are reversibly induced by axon-associated signals to form myelin and Remak cells.