Fig. 2. Reduced mesenchymal proliferation and increased cell death after loss of the AER in Fgfr2^Msx2-Cre mouse embryos. Phosphohistone H3 (pHH3) immunohistochemistry was used to assess mesenchymal proliferation. Caspase 3 immunohistochemistry and TUNEL assay were used to assess cell death. Hindlimb (A-H) and forelimb (I-T) sections are shown at the developmental times indicated. Insets in G and H show TUNEL labeling on adjacent sections. Insets in S and T show the overall size of the limb buds at E11.5. Data are representative of at least three embryos. Scale bar: 50 µm.