The spinal cord of zebrafish is characterised by distinct classes of neurons along the ventrodorsal axis that resemble in much detail the neurons in the mouse or human spinal cord. Differentiation of specific neurons requires input from various signaling pathways (sonic hedgehog, Notch, Retinoic acid. Wnt, BMP). We have established a transgenic reporter where fluorescent proteins mark motoneurons, interneurons and dorsal sensory neurons. Image analysis software has been developed that allows quantifying the number and position of the neurons along the dorsoventral axis. By exposing embryos to compounds we hope to identify molecules that affect neurogenesis as well as the specific differentiation of the various neuronal classes. Molecules may target one of the involved signaling pathways but we may uncover also new signaling systems involved. The identified molecules may have an application in adult neurogenesis. Since several of the signalling pathways are linked to human cancer this assay may also yield molecules with potential applications beyond neurogenesis.