Molecular analysis of developing TMJ in <i>Foxc1^−/−</i> embryos.

<p><i>In situ</i> hybridization analysis on serial coronal cryosections in <i>Foxc1^+/+</i> (A, C, E, G, I, K) and <i>Foxc1^−/−</i> (B, D, F, H, J, L) mouse heads at E17.5. In (A–L) dashed lines outline the wild-type and bifurcated mutant condyles (cdp and cdp*). (A, B) <i>Scx</i> is expressed in the neural crest-derived disc (arrow) and tendon (red arrowheads) of controls. In mutants, Scx is maintained in the tendon (red arrowheads), but no disc is present. (C–F) <i>Sox9</i> is localized to the proliferating chondrocytes and <i>Acan</i> is localized to the cartilage of the condyle growth plate in wild-type and <i>Foxc1^−/−</i> condylar processes. (G, H) <i>Ihh</i> is localized to the prehypertrophic chondrocytes in wild-type and mutant condyles. (I, J) <i>ColX</i> is expressed in the zone of the hypertrophic chondrocytes of the condylar growth plate. In the absence of <i>Foxc1</i>, the hypertrophic chondrocytes make up a larger proportion of the abnormally bifurcated condyle. (K, L) <i>Coll</i> expression is localized to the osteoblasts of the condyle in control and <i>Foxc1^−/−</i> embryos; however, the <i>Coll</i> positive glenoid fossa (f) is only observed in control specimens.