SHH and hydrops fetalis: Together with the known function of DP cells in inducing HF (Jahoda and Reynolds, 1993), and the fact that the de novo folliculogenesis in the K14-Cre; Smof/f and K14-Cre; Smo−/f mutants was confined to haired skin, these results point to the involvement of a Shh-dependent mesenchymal input required to induce de novo HF.