Hedgehog signaling in germ cell migration

The primitive gonad of the Drosophila embryo is formed from two cell types, the somatic gonad precursor cells (SGPs) and the germ cells, which origina te at distant sites. To reach the SGPs the germ cells must undergo a comple x series of cell movements. While there is evidence that attractive and rep ulsive signals guide germ cell migration through the embryo, the molecular identity of these instructive molecules has remained elusive. Here, we pres ent evidence suggesting that hedgehog (hh) may serve as such an attractive guidance cue. Misexpression of hh in the soma induces germ cells to migrate to inappropriate locations. Conversely, cell-autonomous components of the hh pathway appear to be required in the germline for proper germ cell migra tion.