Fig. 2. Irx1 and Irx3 are necessary for kidney formation in Xenopus. Embryos are shown in lateral views; red arrowheads indicate the kidney territory. Embryos were injected in a single blastomere (V2.2) at the 8- to 16-cell stage and lacZ mRNA was used as linear tracer. Control and injected sides of the same embryo are shown, respectively, of the same specimen. The gene examined in each condition is indicated in the right upper corner of the panels in all figures. (A-H) Embryos injected with MOIrx1 showed reduced Lim1 expression at late neurula (A,B) and downregulation of Sglt1k (C,D), Nkcc2 (E,F) and Nbcc1 (G,H) expression at tadpole stages. Inset in (A) indicates a transverse section of the embryo shown in the major panel. (I-P) Similar results were found upon MOIrx3 injection.