• somites;
  • sclerotome;
  • long-term fate mapping;
  • salamander;
  • vertebral column


Cover illustration. In amniotes, single vertebrae derive from the sclerotomes of two adjacent somites. However this process of resegmentation is poorly studied in anamniotes. In this issue of the Journal of Morphology, Piekarski and Olsson (pp. 141–152) provide experimental evidence that resegmentation occurs in a species of amphibian. Their results now provide evidence for wider generality of the resegmentation process across vertebrates. The cover image shows a scanning electron micrograph of an axolotl embryo at early tailbud stage. The epidermis has been removed from the left side of the embryo to reveal underlying structures. Cells of the cranial neural crest (marked green) migrate ventrally in distinct streams. The paraxial mesoderm in the dorsal trunk region is segmented into somites, which give rise to vertebrae by resegmentation.