In many tissues, including the legs of flies, these two genes are essential for proper development. In Drosophila legs, wg is expressed in the ventral region and dpp in the dorsal region where they pattern those respective domains.
Imaginal discs are sacs of tissue that give rise to adult appendages and body parts in Drosophila.
Heslip, T., Theisen, H., Walker, H., and Marsh, J.L . Dsh and Sgg are directly involved in repression of dpp and autoactivation of wg . Theisen, H., Haerry, T.E., O'Connor, M.B., and Marsh, J.L . When Dpp signaling is intact, ectopic wg expression never leads to ventral wg -like cell fates but rather gives lateral cell fates. Haerry, T.E., Heslip, T., Marsh, J.L .