Figure 3 .

TEM of the renal stem/progenitor cell niche after fixation in GA and cupromeronic blue. Low (a), higher (b) and high (c) magnifications illustrate the interstitial interface (asterisk) at the tip of a CD ampulla labeled by a cross (+). (a) Low magnification depicts that numerous protrusions (arrow) from mesenchymal stem/progenitor cells contact the basal lamina at the tip of a CD ampulla covering epithelial stem/progenitor cells. The interstitial space between both kind of tissues appears bright (asterisk). (b) Higher magnification demonstrates that braces of proteoglycans line along the basal lamina of epithelial stem/progenitor cells within the CD ampulla. At the the lamina rara (L.r.) and lamina densa (L.d.) label is lacking, while along the plasma membrane and the lamina fibroreticularis (L.f.) numerous cupromeronic blue labeled molecules (filled arrow head) can be seen. The label is lining to adjacent cell protrusions of mesenchymal stem/progenitor cells (arrow). The interstitial interface appears bright. (c) High magnification demonstrates cupromeronic blue labeled proteoglycans (filled arrow head) at the bright interstitial interface (asterisk). Clear arrow head marks fibers at the lamina fibroreticularis.