Fig. 4. Effects of loss of Odd1 on nephric duct and mesonephric tubule development. Odd1 heterozygous (A,B,E) and homozygous null (C,D,F) mouse embryos stained by whole-mount in situ hybridization for Lim1 (A-D) or Pax2 (E,F). B and D show sections through the mesonephric region. In homozygous null embryos, the nephric duct is thinner and often interrupted (C, left arrowhead in D). A few mesonephric tubules form in the null mutants (F, arrowhead), but fewer than in the heterozygotes (E, arrowheads). In Odd1 mutants, the nephric duct also does not turn normally toward the midline at the posterior end (arrows in E,F). (G,H) Sections through the mesonephric region of E10.5 embryos stained with immunofluorescence against the indicated antigens. Tubules are smaller in mutant (H) compared with control (G) embryos. In both mutant and control embryos, Pax2 is expressed in the nephric duct and the tubules, while Wt1 is expressed in the proximalmost part of the tubule (arrow), as well as in the mesenchyme and coelomic lining. d, nephric duct; t, tubules.