Fig. 2. Expression patterns of Shh signaling genes in developing urogenital tissues. Shh is expressed in the cloacal epithelium, internal urethra, bladder and urethral plate (A-C). Serial tissue sections reveal Ptc1 (D-F) and Gli1 (G-I) expression in the adjacent mesenchyme. At E10.5, both Ptc1 (D) and Gli1 (G) are expressed in the PCM (yellow box). At E11.5 and E13.5, both genes are expressed in the mesenchyme surrounding the urethra, bladder and urethral plate (E,F,H,I). (J) Schematic depicting urogenital organs adjacent to the limb and the tail at E13.5. Shh-expressing epithelia are shown in red. b, bladder; bw, body wall; c, cloaca; cm, cloacal membrane (the ventral side of the cloaca composed by inner endodermal epithelia with surface ectoderm); gt, genital tubercle; hg, hindgut; pcm, peri-cloacal mesenchyme; r, rectum; u, internal urethra; uc, umbilical cord; up, urethral plate.