Suppression of Hair Follicle Development Inhibits Induction of Sonic Hedgehog, Patched, and Patched-2 in Hair Germs in Mice

The study investigated the role of Sonic hedgehog (Shh) signaling in hair follicle formation by examining the expression of Shh and its receptor genes, Patched (Ptc) and Patched-2 (Ptch2), in mice. It was found that these genes were significantly induced in normal embryonic hair germs but their induction was almost completely inhibited in two experimental systems: developing skin tissue of ICR mice cultured with epidermal growth factor and Tabby mutant mice embryos, a model for hypohidrotic ectodermal dysplasia. However, Shh signaling was induced in Tabby embryos at a later stage, suggesting its involvement in the formation of different hair types. The study highlighted the potential of these systems for exploring molecular mechanisms in early hair follicle development.