Mice that were homozygous for the Dab1 cKI allele (A-E) or homozygous for the Dab1 cKI allele and carried a tamoxifen inducible Cre transgene (Cre-ERTM; F-J) were injected with tamoxifen at P3 and analyzed for Dab1 and β-galactosidase expression (βG) (B,G), nuclear fast red (FR) and β-galactosidase activity (C,H) at P7, or analyzed by Golgi staining at P60 (D,I). Hematoxylin staining of the hippocampus shows that neuronal cell body position is relatively normal in Dab1 cKI homozygous animals in the absence or presence of the Cre-ERTM transgene at P7 (A,F, respectively) and P60 (E,J, respectively) in tamoxifen treated animals. Pyramidal neurons from the CA1 region of the hippocampus of adult animals have the basic morphology characterized in the diagram. Golgi stained neurons from the CA1 region of the hippocampus were analyzed in two control groups of mice that didn’t carry the Cre-ERTM gene but were treated with tamoxifen (K,L), and mice that carried the Cre-ERTM gene but were not treated with tamoxifen (M,N), as well as one group of experimental animals that carried the Cre-ERTM transgene and were treated with tamoxifen (O,P). The neuronal morphologies displayed are representative of those observed in several sections of at least three brains from each treatment group. SO, stratum oriens; SP, stratum pyramidale; SR, stratum radiatum; SLM, stratum lacunosum moleculare. The scale bar is 500 μm in G, J and 20 μm in H, P.