(A–E) P12 normal skin. (F–J) P12 mutant skin. (K–N) P12 normal oral cavity. (O–R) P12 mutant oral cavity. Stained with H&E for histology (A, F, K–L, O–P), Ki67 (B, G), β-catenin (C, H, M, Q), K14 (D, I, N, R), and K6 (E, J). Aberrant follicular morphogenesis, characterized by formation of irregularly spaced, nonpolarized hair follicles, in mutant skin is evident. Despite the abnormal histology, proliferation seems to be confined to hair bulb-like structures (arrows in [G], inset [G′] at higher magnification), but in mutant skin (arrows in [H], inset [H′] at higher magnification) and oral cavity (arrows in insets [Q′] at higher magnification) elevated cytosolic localization of β-catenin is detected in some cells. Scale bars: 50 μm for (A–F), (H–J); 250 μm for (K) and (O); 100 μm for (G), (L–N), (P–R); 20 μm for (Q′).