
Cover image: Flour beetle (Tribolium) embryos that do not express the developmentally regulated caudal gene. Caudal expression is necessary for axis elongation and body segmentation in arthropods that generate segments from a posteriorly located growth zone. Elimination of caudal causes the arthropod to develop only a head. See the article by Copf et al. on pages 17711–17715. Photograph courtesy of Reinhard Schröder.