Mechanisms and Evolution of Dorsal-Ventral Patterning

In the last two decades, a great progress has been made with the discovery and understanding of conserved signaling pathways, in particular those involved in embryonic dorsal ventral patterning and the organization of the nervous system. Remarkably, the spatial distribution of these signal molecules appears conserved across a large group of animals that have centralized nervous systems. Despite these achievements, there are still many unanswered questions on how the nervous system organization evolves and responds to variations in organism size. In this review, we discuss the progression of the field from early observations made more than a century ago and introduce future challenges regarding the problem of scaling of the nervous system during evolution.