Figure 1.

Phenotypes of skin specific Shh knockout mice. (A) Note hairs protruding onto the skin surface in wild-type (WT) pups at P5 and hair coat forming at P8. Shh knockout (KO) pups showed a complete lack of visible hairs, including whiskers. (B) Primary hair germs were formed in the WT embryos at E15 with a clear dermal condensation under each germ (arrow). In Shh knockout pups, primary hair germs were formed on time, but dermal condensations were rudimentary. (C) WT mice started to make hair shafts at P5 (lower left part), but knockout mice still remained at the germ stage (upper left part). Dermal condensations had disappeared in the knockout mice at P5 (insert in P5 KO). At P8, knockout skin showed invaginations at the site of hair follicle germs (upper right part). Higher magnification showed follicular keratosis with keratotic plugging (lower right part). Arrowheads point to a hair germ.