Fig. 1. Expression pattern of the Gli family of transcription factors. Sections of E14.5 (A,C,E,G,I) and E16.5 (B,D,F,H,J) wild-type limbs were hybridized with antisense riboprobes as indicated. At E14.5 Gli1 (C), Gli2 (E) and Gli3 (G) are expressed in proliferating chondrocytes distal to the Ihh (A) expression domain. In the perichondrium low levels of Gli2 and Gli3 and strong levels of Gli1 expression can be detected (yellow arrow, C,E,G). In elbow and carpal joints Gli3 is strongly expressed and Gli2 weakly expressed, overlapping with PTHrP (I) expression. At E16.5 Gli1 is uniformly expressed in proliferating chondrocytes (D). By contrast there is a decreasing gradient of Gli2 and Gli3 expression from distal (red arrows F,H,) to central. All three Gli genes are additionally expressed in the chondro-osseus junction (green arrow, D,F,H) and in the perichondrium. Ulna is up and radius is down.