ADHESION AND SIGNALING IN AXONAL FASCICULATION

Numerous in vitro assays and in vivo perturbation studies have led to a model of neural development in which selective fasciculation helps t o define accurate axonal projections, Genetic analysis in vivo confirm s the hypothesis that axonal fasciculation and defasciculation are con trolled by adhesion mechanisms, but also suggests that, in many cases, adhesion and guidance are separable phenomena. In addition, receptors that control the level of tyrosine phosphorylation may play an import ant role in fasciculation, suggesting that complex intracellular pathw ays lie just beneath the surface.