 Studies of Dpp in Drosophila have led to greater understanding of the function and importance of their homologs in vertebrates like humans.Dpp is a classic morphogen, which means that it is present in a spatial concentration gradient in the tissues where it is found, and its presence as a gradient gives it functional meaning in how it affects development.The most studied tissues in which Dpp is found are the early embryo and the imaginal wing discs, which later form the wings of the fly.