Fig. 1. Wnt signaling reporter expression during ventral dermal cell development. (A-F) X-gal-stained transverse sections of TCF/Lef-lacZ embryos at the forelimb (FL) level. (A-C) lacZ expression is detectable in the somatopleure at E8.5, and in the subectodermal mesenchyme cells in the flank at E9.5 and E10.5. (D) At E11.5, expression of the TCF/Lef-lacZ transgene expands to the midline and is visible throughout the subectodermal mesenchyme (arrows and inset). (E) At E14.5, during dermal cell differentiation, lacZ is expressed extensively in dermal cells (arrows and inset), and in the hair follicle placode (hf). (F) At E11.5, in the conditional absence of β-catenin in En1-expressing cells, TCF/Lef-lacZ expression is absent in the entire subectodermal flank and ventral mesenchyme (arrows, inset), but lacZ is expressed in cells of the limb mesoderm where En1 is not expressed (small arrows). (G) When β-catenin activity is stabilized in En1-expressing cells, nuclear β-catenin is ectopically visible in the En1-lineage cells away from the ectoderm (arrows). Compare F and G with D.