Fig. 5. Nephric cord extension in Gata3^-/- embryos. Control Gata3^+/+ or Gata3^+/- embryos (A,C,E,G,I,K) and Gata3^-/- embryos (B,D,F,H,J,L) were analyzed for marker expression on sections of caudal E9.75 mesonephros (A-F) and E10.5 metanephros (G-L). (A,B) Pax2 (red) and Wt1 (green) antibody staining reveals the presence of Pax2⁺ Wt1⁺ nephric cord cells (nc; yellow), but an absence of Pax2⁺ Wt1^- nephric duct cells in Gata3^-/- embryos. (C,D) Immunostaining of the epithelial marker E-cadherin (green) further reveals the absence of a nephric duct in Gata3^-/- embryos (asterisk). Some non-specific signal caused by blood cell autofluorescence is apparent and reflects Gata3-dependent hemorrhages (white arrowhead) (Pandolfi et al., 1995). (E,F) TUNEL signals (red) indicated an increase in apoptosis in Gata3^-/- nephric cord cells. Sections C-F were counterstained with DAPI (blue). (G,H) In situ hybridization with a Pax2 cRNA probe showed the presence of reduced levels of Pax2 expression in the metanephric mesenchyme (mm) in the absence of a ureteric bud (ub). (I,J) The lack of a ureteric bud at the hindlimb level of Gata3^-/- embryos was confirmed by the absence of Emx2 mRNA expression. Emx2 expression in surrounding tissues was unaffected. (K,L) Wt1 mRNA expression in the metanephric mesenchyme is still detected in Gata3^-/- embryos.