Figure 1. Nephron deficit in germ-line p53^−/− and CM^p53−/− kidneys.

A, B) p53^−/− kidneys exhibit 50% fewer and less complex LTA-positive proximal tubules. Metanephroi were harvested at E11.5, cultured on trans-well filters for 72 h and stained for cytokeratin and LTA. LTA counts were averaged from kidneys collected from at least 4 embryos. Mutant kidneys exhibit significantly fewer LTA+ structures than wild-type kidneys (p<0.005). C) E17.5 kidneys were harvested from embryos from p53^+/− crosses, formalin-fixed and sectioned for immunostaining (Methods). Sections were stained with WT1 and cytokeratin antibodies. P53^−/− kidneys show paucity of WT1 stained nephrons. D) Kidneys from mice with conditional p53 deletion from Six2+ cap mesenchyme (CM^p53−/−). Hypoplasia persists post-natally, shown in P0 kidneys, top panels at 4x. Bottom panels (x10) show fewer Lhx1-positive nascent nephrons (red). At P0, 6/8 (75%) examined CM^p53−/− kidneys were hypoplastic compared to wild-type littermate kidneys (n = 8).