Patterning the protochordate neural tube

The complex vertebrate nervous system has evolved from a simpler nervous sy stem such as that seen in present-day protochordates. Through a recent accu mulation of gene-expression data, together with fine anatomical studies. we are now able to identify both how the neural tube was patterned when it fi rst evolved and what is truly novel in the vertebrate neural tube. We are e ntering a new era in the understanding of how the evolution of novel verteb rate structures is linked to genetic evolution.