Positioning and differentiation of veins in the Drosophila wing.

Morphogenesis is the process by which structures with characteristic sizes, proportions and patterns of cell differentiation are generated during the development of multicellular organisms. How the elaboration of pattern is related to cell proliferation and growth control is a critical aspect of morphogenesis. The imaginal discs of Drosophila are a suitable model in which this can be investigated at cellular and molecular level, and recent genetic and developmental analysis has identified some of the key genes and mechanisms that participate in the regulation of their growth and patterning. This review will focus on the formation of the venation pattern in the adult wing, particularly on: 1) the subdivision of the wing blade into domains of gene expression that position the veins, and 2) the cell-cell signaling pathways that participate in the final differentiation of veins.