Six1 expression localized by WMISH. (A–C) and as injected recombinant BAC six1::gfp (D, G). A) Six1 mRNA in mesenchyme blastula is confined to the aboral nonskeletogenic mesodermal domain. B, C) Six1 mRNA is enriched in scattered cells underlying the aboral ectoderm, likely to be pigment cells. D–I) Injected six1::gfp BAC (green fluorescence, D, G) co-expresses with a gcm reporter (red, E, H) in vegetal plate mesoderm at the blastula stage and in the pigment cells of two day embryos; F and I are merged images of panels shown to the left.