Branching Morphogenesis: From Cells to Organs and Back

Many animal organs, such as the lung, the kidney, the mammary gland, and the vasculature, consist of branched tubular structures that arise through a process known as "branching morphogenesis" that results from the remodeling of epithelial or endothelial sheaths into multicellular tubular networks. In recent years, the combination of molecular biology, forward and reverse genetic approaches, and their complementation by live imaging has started to unravel rules and mechanisms controlling branching processes in animals. Common patterns of branch formation spanning diverse model systems are beginning to emerge that might reflect unifying principles of tubular organ formation. Outline 1 Introduction 2 Branching in different organ systems 3 The tracheal system of Drosophila 4 The vasculature 5 The lung 6 The kidney 7 The mammary gland 8 Regionalization of branches during outgrowth: Generation of tip versus stalk 9 Control of cell behavior during the branching process: A comparison 10 Branch outgrowth: Reiteration of a basic process? 11 Methods of choice to understand branching morphogenesis