Figure 6

Illustration of detected structures at the interstitial interface within the renal stem/progenitor cell niche. (a) Mesenchymal stem/progenitor cells are separated from the epithelial stem/progenitor cells within the CD ampulla (A) by an extended interstitial interface (asterisk). Capsula fibrosa (CF). (b) After fixation with GA the interstitial interface (asterisk) is limited by the basal lamina of the CD ampulla. It consists of a lamina rara, lamina densa and lamina fibroreticularis. (c) After fixation in GA containing cupromeronic blue proteoglycans can be recognized lining along the basal lamina of the CD ampulla and protrusions of mesenchymal stem/progenitor cells. (d) Fixation with GA and ruthenium red shows a dense band along the basal lamina of the CD ampulla and numerous clouds of amorphous extracellular matrix within the interstitial space (asterisk). (e) Fixation with GA and tannic acid exhibits label at the basal lamina of the CD ampulla and bundles of extracellular matrix in the interstial interface (asterisk). (f) Merge of information found in illustrations b-e. It can be recognized that fixation with GA (b) does not depict extracellular matrix within the interstitium of the renal stem/progenitor cell niche. Label with cupromeronic blue (c), ruthenium red (d) and tannic acid (e) illustrates that the interstitial interface contains extracellular matrix. Cupromeronic blue (c), ruthenium red (d) and tannic acid (e) do not label the same but different kinds of molecules. Clear arrow head marks fibers at the lamina fibroreticularis. Arrow labels protrusions of mesenchymal stem/progenitor cells, filled arrow head illustrates labeled proteoglycans