Genetics of morphogen gradients

The organization of cells and tissues is controlled by the action of 'form- giving' signalling molecules, or morphogens, which pattern a developmental field in a concentration-dependent manner. As the fate of each cell in the field depends on the level of the morphogen signal, the concentration gradi ent of the morphogen prefigures the pattern of development. In recent years , molecular genetic studies in Drosophila melanogaster have allowed tremend ous progress in understanding how morphogen gradients are formed and mainta ined, and the mechanism by which receiving cells respond to the gradient.