Figure 4: Electron microscopy on renal tubules generated for 13 days at the interface of an artificial interstitium. (a) Scanning electron microscopy demonstrated tubules (T) in the vicinity of polyester fibers (PF). On the surface of tubules single interstitial cells and synthesized fibers of extracellular matrix were observed. (b) Transmission electron microscopy depicted that generated tubules contain a polarized epithelium. Between the apical and lateral plasma membrane a junctional complex was developed (arrow head). (c) Higher magnification illuminated that at the basal side of epithelial cells a basal lamina was found consisting of a lamina rara interna (L.r.i.), a lamina densa (L.d.) and a lamina fibroreticularis (L.f.).