Biocompatible synthetic or natural scaffolds are provided for the reconstruction, repair, augmentation or replacement of organs or tissue structures in a patient in need of such treatment. The scaffolds are shaped to conform to at least a part of the organ or tissue structure and may be seeded with one or more cell populations. Inserts, receptacles and ports are also provided for the attachment of tubular vessels to the neo-organ scaffolds. The seeded scaffolds are implanted into the patient at the site in need of treatment to form an organized organ or tissue structure. The scaffolds may be used to form organs or tissues, such as bladders, urethras, valves, and blood vessels.