Figure 1. Flowchart of the experimental outline. (a) In-vitro assay for cell aggregation of fetal renal cells. Fetal metanephros were dispersed by enzymatic treatment. After centrifuging, cell aggregation was cultured for seven days. (b) In-vitro assay for renal cell aggregation with or without co-culture of spinal cord. Reaggregated spheroids prepared as described before were co-cultured with or without spinal cord for three days to test them for histological maturation. (c) In-vivo transplantation of reaggregated spheroids under the renal capsule of immunodeficient mice. The reaggregated spheroids prepared as already described were transplanted using the new transplantation method developed in this study.