Fig. 5. Gdnf expression is reduced in the Npnt-null embryonic kidney at E11.5 but is normal at E10.5 and E13.5. (A-P) Transverse sections through Npnt^+/+ and Npnt^-/- embryos. (A-H) Expression at E11.5 of the genes indicated, as detected (A-F) by in situ hybridization or (G,H) by immunostaining. (A,B) Note the apparent absence of Gdnf RNA in the MM of the mutant (demarcated by dotted circles), whereas the level of Gdnf expression appears comparable in the adjacent limb bud (arrows) in mutant and wild-type embryos. (C-F) Note that expression of the Eya1 and Six2 transcription factor genes is similar in mutant and wild-type MM. (G,H) PAX2 protein is detected in both the UB (solid arrowhead) and its branches (open arrowhead), as well as in the MM. Note the lack of invasion of the UB into the MM of the Npnt mutant (asterisk). (I-L) Expression at E10.5 and (M-P) at E13.5 of the genes indicated, as detected by in situ hybridization. Note that Gdnf and Eya1 expression appears comparable in Npnt^+/+ and Npnt^-/- embryos at these stages, although the mutant embryonic kidneys are smaller than normal at E13.5. Scale bars, 100 µm. Abbreviations as in previous figures.