The morphogenesis of the olfactory sensory organ of the zebrafish is a unique model for studying cellular motility involved in the maturation of the olfactory epithelium (OE) into a rosette-shaped cluster derived from a row of aligned cell delimitating an arc around the forebrain, the telencephalon. This olfactory morphogenesis has been shown to require the Cxcl12a/Cxcr4b axis, a well-known chemotaxis chemokine involved in many aspects of cellular differentiation and organogenesis. However, the expression pattern of cxcl12a in the telencephalon and the activation of the elicited pathway in olfactory cells are still not characterized. To understand these processes, we developed an agent based mathematical model mimicking OE morphogenesis. We then used the infra-red laser evoked gene operator technique to control gene expression in time and space during live imaging to test the outcome of the mathematical model. In conclusion, our results, combined with a virtual representation of the activation of the Cxcl12a pathway, allow us to propose that a model of mosaic and heterochronic activation of this pathway allows collective migration to form the olfactory epithelium.
