Fig. 7.

Wnt7a loss causes the growth of ectopic nail-like structures. (A) Ectopic nail-like structures growing on the dorsal (and, rarely, on the ventral) surfaces of fore and hind feet of Wnt7a^−/− mice at ∼P180. Dorsal (left) and ventral (right) views of one hind foot are shown in the central two panels. (B) Panels Ba and Bb show Methylene Blue-stained sections of epon-embedded feet at ∼P60 showing a normal nail bed (Ba) and an ectopic nail-like structure on the dorsal surface of the foot (Bb). Inset in Ba shows nail bed anatomy, with the region shown in the image in Ba enclosed in the red rectangle. Panel Bc shows a frozen section through the dorsal surface of a digit at ∼P20, immunostained with mAb AE13, which recognizes hair and nail cytokeratins. The true nail/claw is at the right side of the image and an ectopic nail-like structure is on the left side. Scale bars: 200 μm (Ba,Bb); 1 mm (Bc).