Figure 3.

Histological and molecular phenotype of E13.5 Alk3^UB−/− kidneys. (A through C) At E13.5, Alk3^UB−/− kidneys exhibited moderate (B) to severe (C) reductions in size and number of mesenchyme- and ureteric bud–derived tissue elements. (D through F) DBA-stained E13.5 Alk3^UB−/− kidneys and replica stick figures (G through I) Alk3^UB−/− mutants are characterized by a variable decrease in ureteric bud branch number. Some mutants show a moderate decrease (E and H), whereas others demonstrate a severe decrease as well as dilation of ureteric bud tips (F and I). (J through L) Pax2 expression is reduced in the ureteric bud (arrow) in E13.5 moderately affected Alk3^UB−/− mutants, whereas in severe mutants Pax2 is reduced in both the ureteric bud and mesenchyme. (M through O) WT-1 expression is markedly reduced in moderately affected mutants (arrowhead) and is undetectable in severe mutants. Scale bars (A through O) = 100 μm.