Pathogenesis of cystic kidneys

Multiple cysts in kidneys are never caused by failure of nephrons to connect with collecting tubules. They are of several varieties and are caused by abnormalities of collecting tubule ampullae which lead to reduced or abnormal branching of collecting tubules and inhibition of nephron induction or by secondary enlargement of different parts of collecting tubules or nephrons or both whose architecture is fundamentally normal. In some types, the bile ducts in the liver are similarly affected.