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Figure S2. Cell proliferation and apoptosis in the hindlimb of X. tropicalis and X. laevis. Developing limbs were immunostained for cell proliferation (phosphorylated Histone H3) and apoptosis (active Caspase 3). A-D, Distributions of phosphorylated Histone H3-positive cells in stage 54 and stage 55 limb buds of X. tropicalis (A, B) and X. laevis (C, D). Cell proliferation was evident throughout the limb bud. E-H, Distributions of active Caspase 3-positive cells in stage 54 and stage 55 limb buds of X. tropicalis (E, F) and X. laevis (G, H). Physiological apoptosis was enriched in the apical ectodermal ridge (AER). Note that no detectable difference in cell proliferation or apoptosis was observed between X. tropicalis and X. laevis at these stages. Arrowheads indicate regions where the prehallux anlage is formed. Images are ventral views. Distal is left and anterior is top. Scale bars: 200 μm. |
