Renal Branching Morphogenesis

The human kidney is composed of an arborized network of collecting ducts that converge at the urinary calyces and pelvis to facilitate urine excretion. The renal collecting system arises from the ureteric bud (UB), a derivative of the intermediate mesoderm–derived nephric duct that responds to inductive signals from adjacent tissues via a process termed ureteric induction. The UB subsequently undergoes a series of iterative branching and remodeling events in a process termed renal branching morphogenesis. Formation of the renal collecting system is completed by the 34th week of gestation in humans. Perturbations in patterning of the nephric duct, ureteric induction, or renal branching morphogenesis leads to a spectrum of malformations collectively termed congenital anomalies of the kidney and urinary tract. In this chapter, we describe critical morphogenetic and cellular events that govern nephric duct specification, UB induction, renal branching morphogenesis, and cessation of renal branching morphogenesis.