2. A Brief Outline of the Hedgehog Pathway Hh genes are found throughout the animal kingdom. Vertebrates have three hhs: Desert hedgehog (Dhh), Indian hedgehog (Ihh) and Sonic hedgehog (Shh), although Ihh and Shh have undergone J. Dev. Biol. 2016, 4, 36 3 of 22 2. A Brief ...