Abstract: The spine is a segmented axial structure comprised of alternating vertebral bodies (centra) and intervertebral discs (IVDs). The current model of spine patterning hinges upon segmentation of the embryonic paraxial mesoderm (PM) and its subsequent re-segmentation and condensation around the notochord to produce the characteristic alternating pattern of centra and IVDs. While mutations in segmentation genes are known to cause spine defects, whether this machinery primarily affects patterning of the PM, the notochord, or both remains unknown. Thus, a complete understanding of how PM-derived cells migrate to the notochord to produce sharp vertebral segments separated by regular gaps remains unresolved. Using a zebrafish model, we will follow a comprehensive approach combining live imaging, transcriptomics and genetic manipulations to dissect the role of the notochord in the specification of vertebral segments and IVDs. Understanding the cellular and molecular mechanisms acting in the notochord during spine segmentation will provide a more complete understanding of vertebral patterning.