Figure 4. Neither collecting duct epithelium or renal endothelium arises from the cap mesenchyme.

Cited1-CreER^T2/R26R^LacZ mice were injected with tamoxifen at E13 and lineage was examined by staining with anti-β-Galactosidase antibodies at 6 weeks of age. A–B′, Staining of sequential sections with anti-β-Gal (A, A′) and anti-Aqp2 (B, B′) demonstrates that cap mesenchyme derived cells do not populate the collecting duct epithelium. LacZ positive cells (arrows) are closely opposed to, but distinct from, Aqp2 positive collecting ducts (arrowheads). Position of one of the collecting ducts is indicated with dashed white lines, illustrating lack of overlap with β-Gal staining. C/D, Immunoperoxidase staining using anti-Aqp2 on sections which have been β-Gal stained shows that cap mesenchyme derived cells (arrows) do not overlap with either cortical (I, arrowheads) or medullary collecting ducts (J, arrowheads). Gl–glomeruli. E–G, Cap derived cells (E) and PECAM1 positive endothelial cells (F) do not overlap in glomeruli (G). H–J, Elongated cap mesenchyme progeny in the medulla (H, arrows) do not coincide with PECAM1 positive endothelium (I, arrowheads) but instead run alongside their closely associated vasculature (J).