Fig. 8. Early defects in chondrogenesis and gene expressions affected in the CAG-CAT-Mesp2;Mox1-Cre double heterozygotes. Skeletal morphology was revealed by Alcian Blue staining in the wild-type (A) and double heterozygous (B) embryos at 13.5 dpc. (C-H) Uncx4.1. expression was reduced in double heterozygotes (D,F) at both 10.5 (C,D) and 11.5 dpc (E,F) compared with wild-type embryos (C,E). The section of 11.5 dpc embryonic tail revealed Uncx4.1-negative cells (arrowheads) in the caudal compartment of somites in the double heterozygote (H). Comparison of expression patterns of Pax3 (I,J), Sox9 (K,L) and Tbx18 (M-P) between wild-type (I,K,M,O) and double heterozygous (J,L,N,P) embryos. Outlines in K and L show Sox9 expression in the rib primordia.