Involvement of Slit-Robo signaling in the development of the posterior commissure and concomitant swimming behavior in Xenopus laevis.

Introduction: During vertebrate development, the central nervous system (CNS) has stereotyped neuronal tracts (scaffolds) that include longitudinal and commissural axonal bundles, such as the medial longitudinal fascicle or the posterior commissure (PC). As these early tracts appear to guide later-developing neurons, they are thought to provide the basic framework of vertebrate neuronal circuitry. The proper construction of these neuronal circuits is thought to be a crucial step for eliciting coordinated behaviors, as these circuits transmit sensory information to the integrative center, which produces motor commands for the effective apparatus.