Fig. 1.

Specific domains of ERK pathway activation in the craniofacial region. P-ERK1/2 immunostaining (red) in the palatal shelves (A-C), tongue primordium (D-F) and mandible (G-I) of control mice at E12.5, E13.5 and E14.5. In A-C, arrowheads indicate signals in the epithelium whereas arrows indicate signals in the mesenchyme. In D-F, arrowhead indicates signals in the neural crest-derived mesenchyme whereas arrows indicate signals in the muscle. In G-I, arrowheads indicate signals in the chondroblasts of the Meckel's cartilage whereas arrows indicate signals in the osteogenic progenitors. Yellow arrows indicate the location of terminally differentiated osteoblasts. n=3 for each stage. Scale bars: 100 µm.