Expression of the TCF/Lef-LacZ transgene from E8.5 to E12.5. Lateral (A) and dorsal (A') views of an E8.5 embryo stained for ß-galactosidase activity. Sections through the same embryo show staining in the NCC (A1), the presomitic mesoderm (A2, A4), notochordal plate (A2) and ectoderm (A3). (B) Lateral view of an E9.5 embryo positive for the transgene and sections through it, revealing expression in the brain (B1), NCC (B2, B4), notochord, nephric duct and faintly in the neural tube and somites (B3). (C) Expression of the transgene in an E10.5 embryo and transverse sections (C1, C2) along the indicated planes show staining in the limb, neural tube, gut and tail bud. (D) Whole mount view of an E12.5 embryo stained for ß-galactosidase activity. Sections through the same embryo reveal staining in the lung buds (D1), limb mesenchyme (D2), kidney tubules (D3), eye (D4) and nasal cavity (D5). h, heart; li, limb; NCC, neural crest cells; nph; nephric duct; nt, neural tube; ov, otic vesicle; PSM, presomitic mesoderm; tb, tail bud.