Fig. 1

X-gal staining in mandibular incisors of Bmp7+/− (ICR) and Usag-1+/− (C57BL/6) mice at E14/E15. Tissue sections from mandibular incisors of Bmp7+/− (ICR) and Usag-1+/− (C57BL/6) mice at E14 and E15 were stained with X-gal (a–h). Scale bars indicate 100 μm. a–f Sagittal sections. g, h Coronal sections. a, b, d, e, g Embryos of Bmp7+/− (ICR) mice. Bmp7 was expressed (blue) in the mesenchyme near the tooth germ. c, f, h Embryos of Usag-1+/− (C57BL/6) mice. Usag-1 was expressed (blue) in a small portion of epithelia, except for the enamel knot and the mesenchyme near the tooth germ. a–c Embryonic day 14. d–h Embryonic day 15. a, d Sections near a rudimentary incisor (arrows) with strong expression are shown. b, e Sections near an enamel knot (arrowheads) with strong expression are shown