Fig. 4. Shh and Ptc expression. In situ hybridisation was performed on the dorsal skin of (A-D) untreated wild-type mouse with anagen follicles, (E-H) D2 or (I-L) D4 transgenic mice treated with 4OHT for 7 days, and (M-P) on the dorsal paw skin of D4 transgenic mice treated with 4OHT for 7 days. (B,F,J,N) Dark-field views of Shh in situ hybridisations in A,E,I,M, respectively. (D,H,L,P) Dark-field views of Ptc in situ hybridisations in C,G,K,O, respectively. Arrows in B indicate asymmetric Shh expression in the bulb of the hair follicle, while the arrow in D indicates more uniform Ptc expression in the bulb. Arrows in F,J show Shh expression in the outgrowths arising from the permanent portion of the follicles. Arrowheads in J show abnormal symmetrical expression of Shh in the bulb of the hair follicle and the asterisk in N indicates Shh expression in epithelial downgrowths in the interfollicular epidermis. Scale bars: 100 µm.