The normal development of calvarial bones and sutures critically relies on proper signalling through Fgf receptors, but the source and identity of cognate ligands have remained unknown. Reverse transcriptase polymerase chain reaction analysis in this study shows that a broad range of Fgf ligands are expressed in the coronal sutures separating the parietal and frontal bones. Analysis by whole mount in situ hybridization further reveals distinct expression patterns for Fgf-18, Fgf-20, and by comparison, Fgf-9, in the calvaria, and Fgfs-20 and -9 in the developing limbs, suggestive of their role in proliferation, differentiation and apoptosis.