The world according to Hedgehog

Members of the Hedgebog family of signaling molecules mediate many important short- and long-range patterning processes during invertebrate and vertebrate development. In the fly, a single hedgebog gene regulates segmental and imaginal disc patterning. In contrast, in vertebrates a hedgebog gene family is involved in the control of left-right asymmetry, polarity in the central nervous system (CNS), somites and limb, organogenesis, chondrogenesis and spermatogenesis. Here, we review experiments addressing the function of the various Hedgebog members during invertebrate and vertebrate development.