Fig. 7. Expression of Odd1 inhibits kidney tubule formation. (A-C) Representative control chicken embryos infected with RCAS-Gfp at day 0 and harvested at day 5, showing extensive infection (A) and robust mesonephric tubule formation (A-C). (D-F) RCAS-Odd1 infected embryos analyzed by section in situ hybridization for Odd1 to document extent of infection (D), by Nomarski microscopy (E) and with immunofluorescence for Pax2 (F). The mesonephroi of RCAS-Odd1 infected embryos contain fewer epithelialized tubules (compare B,C with E,F), but do contain significant numbers of Pax2-expressing non-epithelialized cells (arrow in F). When epithelialized tubules are present in RCAS-Odd1 infected embryos, the tubules tend to be uninfected (D), whereas tubules are readily infected by control RCAS-Gfp virus (A) (in situ detection conditions were calibrated to detect only ectopic and not endogenous Odd1 message). The area of total tubular tissue (defined as Pax2-expressing cells arranged either as lumenized epithelia or as aggregates with polarized nuclei) in RCAS-Odd1 infected embryos is significantly smaller than in control embryos (G), but the nephric ducts are approximately the same size (H). Bar graphs show mean and standard error of 8 RCAS-Gfp and 10 RCAS-Odd1 samples. The y-axis is in arbitrary units. d, nephric duct; t, tubule.