Fig. 2. Decreased proliferation in mouse limb bud mesenchyme caused by loss of N-Myc. (A-X) N-Myc expression is shown by in situ hybridization of transverse sectioned limb buds from PC, PC-NMyc^f/f at E9.5, 10.5 and 11.5 as indicated. N-Myc^-/- embryos were analyzed only at E9.5 and 10.5 due to lethality by E11.5. Transverse limb bud sections were stained for BrdU incorporation (brown) and counterstained with Hematoxylin (blue). The boxed regions, representing areas in which N-Myc is expressed or predicted to be expressed in the mutants, are shown at higher magnification (40x of E9.5 sections and 20x of E10.5 and 11.5 sections) in panels on the right.