Fig. 1. Deficient SHH-SMO signaling disrupts kidney development. (A,C,D) Gross anatomical features of kidney development in wild-type and Shh^–/– mice at E18.5. In contrast to wild-type mice (A), Shh^–/– mice exhibited either absence of both kidneys (C) or the presence of a single ectopic kidney located in the pelvis (D). (B,E) Renal histological phenotype in E18.5 mice. In contrast to the organized appearance of glomeruli and tubules in the renal cortex of wild-type mice (B), the single kidney formed in 50% of Shh^–/– mice (E) was characterized by a paucity of glomeruli and the presence of dilated tubules. Scale bar: 100 µm. (F-I) Effect of cyclopamine on renal development. Treatment of mice with cyclopamine starting at E9.5 for four consecutive days blocked renal development. In contrast to kidneys from mice treated with drug vehicle alone (F,G), kidneys in cyclopamine-treated mice (H,I) demonstrated a marked decrease in ureteric bud branches and epithelial metanephric derivatives. Scale bar: 100 µm. (J,K) Ureteric bud branching in embryonic kidneys isolated at E11.5 from wild-type mice. Kidneys from the same mouse were cultured as pairs in the presence of drug vehicle (J, 100% ethanol in culture medium) or cyclopamine (K) for 4 days. Ureteric bud branches were identified with Dolichos Biflorus Agglutinin. In contrast to vehicle, cyclopamine decreased the number of ureteric bud branches formed. Scale bar: 100 µm. G, gonad; K, kidney.