The conversion of intermediate mesoderm into renal tubular structures occurs throughout embryonic development from the formation of the nephric duct through to the generation of metanephric nephrons. Studies using an in vitro model system of renal epithelial morphogenesis indicate that the signals mediating tubulogenesis rescue intermediate mesoderm from programmed cell death, trigger spindle-shaped mesodermal cells to differentiate into epithelia, and lastly promote epithelial cell diversification and segmented tubule assembly. Recent data indicate that members of the Wnt family of developmental regulatory genes play an important role in the signaling pathway mediating renal epithelial morphogenesis.