Functional characterization of the vertebrate primary ureter: structure and ion transport mechanisms of the pronephric duct in axolotl larvae (Amphibia).

Background: Three kidney systems appear during vertebrate development: the pronephroi, mesonephroi and metanephroi. The pronephric duct is the first or primary ureter of these kidney systems. Its role as a key player in the induction of nephrogenic mesenchyme is well established.