Fig. 5. The del5-LacZ transgenic reporter allele detects active HH signaling in vivo. (A) A schematic diagram of the del5-LacZ DNA construct to generate transgenic mice. The promoter contains eight consensus Gli-binding motifs (red ovals) and a basal gamma-crystalline promoter upstream of the LacZ gene. (B-D) LacZ staining was detected in the PCM at E10.5 (A; yellow box and inset) and at subsequent stages in the PCM, urethral plate and bladder (C,D). Note that at E12.5 and E13.5, there is robust LacZ activity in bladder (white arrow) but not in the GT mesenchyme (black arrow). b, bladder; c, cloaca; gt, genital tubercle; u, internal urethra; uc, umbilical cord; up, urethral plate.