FoxA and GATA456 are regionally expressed along the alimentary canal in Chaetopterus and Themiste lageniformis. Lateral views of (left) post-gastrula and (right) larval stages showing a summary of expression in presumptive and definitive gut regions. Colors correspond to individual FoxA and GATA456 expression patterns and overlapping domains where both transcription factors are co-expressed. One GATA456 gene in each species is simultaneously expressed in endoderm and mesoderm. Blue, FoxA; yellow and yellow + red, GATA456; dotted line, yolk-rich interior. en, endoderm; hg, hindgut; mg, midgut; ms, mesoderm; st, stomodeum; vnc, ventral nerve cord.