The normal embryologic development of the kidney: a basis for understanding structural abnormalities.

The embryologic development of the metanephric kidney is a regulated and sequential growth process. The induction of the early precursors of the metanephric kidney (pronephros and mesonephric) are essential first steps for the later appearance of the metanephric kidney. The pathogenesis of cystic disease can now be reexamined in light of these unique but carefully programmed growth processes with the expectation that the specific nature of the several growth disorders responsible can be more clearly defined.