Extracellular matrix molecules that influence neural development.

Abstract

As developing neurons migrate, extend axons, and form synapses, much of their behavior is specific-that is, stereotypes and predictable. It is now clear that intrinsic neuronal predilections do not fully account for this specificity, but rather that extrinsic cues also influence neuronal choices. About ten years ago, experiments in several systems began to implicate the extracellular matrix (ECM) as an important source of this guidance: Contact with matrix was shown to influence neuronal migration, axonal growth, and synaptogenesis, as well as glial differentiation (reviewed in Sanes 1983). Once these phenomena had been documented, attention turned to a search for the ECM molecules that mediate them. Here, I summarize this recent work. In reviewing very new and often preliminary data, I have tried to indicate some general themes that are emerging, but to refrain from drawing prema­ ture conclusions from a rapidly evolving body of work. It has seemed, too, more valuable to be comprehensive than to be critical at this stage, even though this precludes consideration of three areas that form the back­ ground for molecular analysis of neural ECM. First, I have cited few papers published before 1983, and refer the reader to the earlier review (Sanes 1983) for more detailed consideration of previous work. Second, even though most work on ECM in the nervous system relies on earlier studies of nonneural cells, I have omitted this relevant background. Recent reviews on the general biology and biochemistry of ECM include those of Akiyama & Yamada (1987), Buck & Horwitz ( 1 987), Cunningham (1987), Hassell et al (1986), Hynes ( 1987), Mayne & Burgeson (1987), Martin & Timpl (1987), Ruoslahti ( 1 988), Ruoslahti & Piersbacher (1987), and