Figure 6 : Schematic illustration shows possible routes for transmission of morphogenetic factors between mesenchymal (mes),
and epithelial (ep) cells via the interface within the renal stem/progenitor cell niche.

(a) Fixation of specimens by GA suggests that morphogenetic factors are exchanged between epithelial (1) and mesenchymal (2) cells by diffusion
via thebright interface.
(b) Fixation of specimens by GA containing lanthanum, alcian blue and cupromerionic blue suggests that projections of mesenchymal cells contact
the basal aspect of epithelial cells supporting an exchange via cell to cell contacts and diffusion.
(c) Fixation of specimens by GA containing ruthenium red and tannic acid elucidates that projections of mesenchymal cells are integrated in filigree
extracellular matrix. In this case morphogenetic molecules can be exchanged by diffusion, mesenchymal cell projections and modulating extracellular
matrix. The basal lamina consisting of a lamina rara (L.r.), lamina densa (L.d.) and lamina fibroreticularis (L.f.) at the tip of a CD ampulla is marked by
a cross (+).

Minuth et al.Stem Cell Biology and Research  2014 1:4DOI : 10.7243/2054-717X-1-4