Figure 3. Juxtaposition of WNT^hi and WNT^lo Borders Is Sufficient to Acquire Asymmetric Cell Fates.

(A) Immunohistochemistry of Apc^fl/fl epidermis uninfected (top) or LV-Cre-transduced (bottom), generating Apc-null regions with increased WNT activity, indicated by intense β-catenin signal.

(B) Planar confocal IMF of Apc^fl/fl; R26YFP^fl/+ epidermis mosaic for LV-Cre. Note WNT-hyperactivated next to WNT-normal regions establish boundary for asymmetric cell fates.

(C) Planar confocal IMF in Ctnnb1^fl/fl; R26YFP^fl/+ embryos transduced with LV-Cre. Note selective loss of LEF1 in IFE patches where β-catenin is absent.

(D) Planar confocal IMF in Ctnnb1^fl/fl (or ^fl/+); R26YFP^fl/+ embryos infected with high-titer LV-Cre to generate small regions of β-catenin⁺ untransduced cells surrounded by β-catenin⁻ transduced cells.

(E) Sagittal IMF in placode (top) and peg (bottom) of R26YFP^fl/+; Ctnnb1^fl/fl embryos transduced with LV-Cre. Bracket indicates SOX9⁺ IFE halo. Note YFP⁺ SOX9⁺ IFE cells do not contribute to mature HF.

Tissues processed as indicated for immunohistochemistry (β-catenin) or IMF (LEF1, Pcad, LHX2, SOX9, β-catenin, YFP).

Dashed lines in (A,E) indicate basement membrane, in (C), borders between transduced and untransduced regions.

Scale bars in (A), 10μm; in (B,D,E), 20μm; in (C), 50μm.

See also Figure S2.