Embryonic development of the ureter.

During human embryonic development, the ureteric bud, a simple epithelial tube that arises from the Wolffian duct, initiates a cascade of events which results in the formation of the metanephros and its collecting system. In this review, the anatomic and molecular basis of ureteric development are discussed. Although it is difficult to separate metanephrogenesis from ureterogenesis of the proximal segment, the data presented are biased toward the latter. Some of the factors involved in the budding and branching of the embryonic ureter and the maturation of the fetal ureter into a peristaltic conduit are discussed as presently understood. Finally, a brief description of congenital abnormalities in ureteral development is presented with some putative mechanisms.