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Fig. 5. Gene expression in regenerating wild type and N1 limbs and tails. A–H In situ hybridization showing Msx1 expression in tails. Black arrows indicate regions of Msx1 expression in the tail bud or regeneration bud. (A) Wild type (WT) embryo tail during development, expression in dorsal posterior neural tube (arrow) and fin, stage 36. (B) Wild type tadpole tail 1 day after amputation, expression in fin epidermis maintained. (C, D) Wild type tadpole tail 3 and 5 days after amputation, expression re-established in neural ampulla. White arrowheads show level of amputation. (E) Msx1 is not normally expressed in tail core tissues, but only in fin epidermis, as shown in this N1 tail fixed immediately after amputation. (F–H) Msx1 is not re-expressed in heat-shocked N1 tails at 1, 3 and 5 days after amputation. White arrowheads show level of amputation. (I–L) In situ hybridization showing Msx1 expression in limbs, following amputation at future knee level at stage 53. Arrowheads show the level of amputation. (I, K) Wild type (WT) limb 3 days and 5 days after amputation, Msx1 is expressed throughout the blastema tissue but absent from the AEC. (J, L) Msx1 is not expressed in heat-shocked N1 limbs 3 or 5 days after amputation. (M–O) Expression of FGF8 in regenerating tails and limbs. Level of amputation is marked by arrowheads. (M, N) WT tadpole tail 2 and 5 days post amputation, showing expression in fin and blastema (black arrows). (O, P) WT and heat-shocked N1 limbs amputated at knee level at stage 53 and fixed after 3 days. FGF8 expression is seen in WT limbs in the AEC but is detectable only in around 50% of N1 limbs and at lower levels. All scale bars 100 μm. |
