Fig. 3. Shh protein is detectable in epithelium and mesenchyme of the developing tooth germ in a wider distribution than epithelial-restricted Shh. (A,C,E,G) Immunohistochemistry; (B,D,F,H) section in situ hybridisation. (A,B) E11.5 epithelial thickening. (C,D) E12.5 early bud. (E,F) E13.5 late bud. (G,H) E14.5 cap. Shh protein is undetectable in the diastema in the presence of epithelium. (I,J) E11.5 mandibles cultured for 24 hours. (I) Section through the early molar epithelial thickenings (arrows indicate Shh protein in odontogenic epithelium). (J) Section through the diastema demonstrating a lack of detectable Shh protein. (K,L) Immunohistochemistry. Timed-culture of E11.5-isolated mandibular mesenchyme demonstrating the dynamics of Shh detection in the diastema. (K) Shh is first detectable after approximately 20 hours. (L) Shh is strongly detected in the diastema after 24 hours. Shh immunohistochemistry does not cross-react with Ihh. (M,N) E16.5 mandibular condyle. (M) Ihh; (N) adjacent section stained for Shh demonstrating no cross-reaction with Ihh. mc, Meckel's cartilage; t, tongue. Scale bars: in A, 50 µm for A-F; in G, 150 µm for G,H; in I, 600 µm for I,J; in K, 600 µm for K,L; in M, 500 µm for M,N.