  A common developmental process, called branching morphogenesis, generates the
epithelial trees in a variety of organs, including the lungs, kidneys, and
glands. How branching morphogenesis can create epithelial architectures of very
different shapes and functions remains elusive. In this review, we compare
branching morphogenesis and its regulation in lungs and kidneys and discuss the
role of signaling pathways, the mesenchyme, the extracellular matrix, and the
cytoskeleton as potential organ-specific determinants of branch position,
orientation, and shape. Identifying the determinants of branch and organ shape
and their adaptation in different organs may reveal how a highly conserved
developmental process can be adapted to different structural and functional
frameworks and should provide important insights into epithelial morphogenesis
and developmental disorders.
