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. Author manuscript; available in PMC: 2011 Jan 15.
Published in final edited form as: Dev Biol. 2009 Nov 13;337(2):386–395. doi: 10.1016/j.ydbio.2009.11.017

Figure 1. The Six2-GFP∷Cre transgene is expressed mosaically in renal epithelial progenitor population, with uniform high level of expression in the induced mesenchyme and pre-tubular aggregates prior to RV formation.

Figure 1

(A-A") Six2-GFP∷Cre transgene (green) is expressed at variable levels within renal epithelial progenitors. Not all Six2+ cells (red) express GFP∷Cre at E13.5 (arrowheads). GFP∷Cre is expressed at higher levels in cells exiting or no longer in the definitive renal epithelial progenitor pool (arrows) and in pretubular aggregates (*) and continues to be expressed in RV (**). A' is a higher magnification of the boxed area in A. (B and B') Co-staining for Pax2 (red) and the Six2-GFP∷Cre transgene (green) reveals that not all mesenchymal cap condensates that are Pax2+ express Cre recombinase (blue arrowheads) at P1. The white arrowheads are placed as positional references and point at cells expressing both Pax2 and GFP. (C) Importantly, due to strong expression of Cre in pre-tubular aggregates, all cells achieved recombination of floxed alleles by the S-shaped stage as demonstrated by β-galactosidase expression in every S-shaped body cell of E13.5 Six2-GFP∷Cretg;Rosa26R kidneys. All cells of the S-shaped bodies (arrowheads) have experienced cre mediated recombination and have turned on β-galactosidase expression in the E13.5. All scale bars are 100um.