Gross and histological analysis of SOXC mutant embryos. (A) Pictures of E18.5 control and SoxC/Prx1Cre mutants. (B) High-magnification pictures of control and triple mutant feet. (C–E) Foot coronal sections stained with Alcian blue (cartilage-specific dye) and nuclear fast red (AB&NFR). Pictures focus on metatarsals and proximal phalanges. Red and black arrows, anterior–posterior and proximal–distal fusions of cartilage primordia, respectively. (F) Pictures of E11.5–13.5 embryo limbs. FL, forelimb; HL, hind limb. (G) Hind limb coronal sections stained with hematoxylin and eosin (E11.5–12.5) or AB&NFR (E13.5). Distal/proximal and anterior/posterior axes are shown. (H–J) Alcian blue staining of E14.5 whole embryos (H) and sections of hind paws (I) and tibias (J). EC, epiphyseal cartilage; PC, proliferating chondrocytes; pHC, prehypertrophic chondrocytes; HC, hypertrophic chondrocytes. All data were verified more than three times. Each panel shows the results of a typical experiment.