Expression of wnt-3a and fgf-8 in regenerating limb buds. (A and D) Stage 52 limb buds. (B, C, E and F) Regenerating blastemas at 3dpa. Right panels (C and F) show in situ hybridization on sectioned samples. Wnt-3a and fgf-8 are expressed in the inner layer of thickened apical epithelium of the blastema at 3 dpa. No specific hybridization signal was detected with an wnt-3a sense probe (C, inset). Arrowheads show amputation level (knee level). a, anterior; p, posterior; d, dorsal; v, ventral. Scale bars, 100 μm.