COVER PHOTOGRAPH: Collage of two developmental stages of the amphipod Orchestia cavimana. Both 3D-reconstrucitons of CLSM image stacks. Lower image shows an early embryo (dorsal view) with labelled mesendodermal precursor cells of the trunk region in red (DiI in-vivo labelling) and nuclei in blue (DAPI). Blastomeres ba and da were marked at 8-cell stage. Upper image shows an advanced embryo shortly before hatching (lateral view) with musculature in red (Phalloidin) and nuclei in blue (DAPI). The segmental iterative musculature is a derivative of mesoblast cells which have the highly ordered pattern in earlier embryonic stages (shown below). From Hunnekuhl and Wolff, Developmental Dynamics 241:697–717, 2012.