Figure 1: Isolation and culture of renal stem/progenitor cells. (a) Epithelial and mesenchymal nephrogenic stem/progenitor cells were found beyond the organ capsule. For isolation the embryonic tissue layer was stripped off by fine forceps. (b) To generate tubules during culture the tissue was mounted between two layers of a polyester fleece to create an artificial interstitium. (c) The sandwich set-up containing renal stem/progenitor cells was then placed in a culture container. Long term perfusion culture was performed with a peristaltic pump transporting always fresh medium (1.25 ml/h) from the storage bottle to the culture container and then to the waste bottle.