Fig. 3. nacre mutant reveals that fms acts through the xanthophore lineage to promote melanophore stripe formation. (A,B) nacre^- fms^- chimeras reared to adult stages (n=29) that developed donor (nacre^- fms⁺ GFP⁺) xanthophores also developed organized melanophore stripes (n=7). (B,B') Corresponding bright-field and fluorescence micrographs of the individual in A showing donor xanthophores (e.g., red arrow) adjacent to the melanophore stripe. (C) nacre^- fms^- chimeras, lacking xanthophores, failed to develop organized melanophore stripes (n=22). An individual exhibiting donor (nacre^- fms⁺ GFP⁺) iridophores (n=6) is shown. (D,D') Corresponding bright-field and fluorescence views of the individual in C showing donor iridophores (e.g., blue arrow). Note that the orange color in some regions is due to reflections from iridophores rather than differentiated xanthophores. In contrast to melanophore arrangements, however, average melanophore densities did not differ dramatically between nacre^- fms^- chimeras that either developed or failed to develop donor xanthophores (means=373, 316 melanophores/mm², s.d.=111, 69, n=4, 11, respectively; t₁₃=1.0, P=0.3). (E,F) Development of melanophore stripes in nacre^- hosts. (E) Wild-type cells transplanted to nacre^- hosts develop regions of well-formed stripes. (F) fms^- cells transplanted to nacre^- hosts contribute to stripes resembling those formed by wild-type cells. Scale bars, (A,C) 4 mm, (B,D) 100 µm, (E,F) 800 µm.

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