Pyramidal cells from combined APP/APLP2-DKO neurons show additional defects in dendritic complexity compared to APP-KO single mutants. (a) Representative example of 3D-reconstructed CA1 neurons from APP-KO mice (left) and APP/APLP2-DKO mice (right). Note the differences in dendritic complexity: arrowhead indicates an increase in the number of primary basal dendrites in APP/APLP2-DKO neurons. (b) Comparison of the number of primary basal dendrites revealed an increase in APP/APLP2-DKO neurons when compared to neurons from APP-KO mice (APP-KO: 7.10 ± 0.43 versus APP/APLP2-DKO 8.89 ± 0.79; Student’s t-test, *p ≤ 0.05, APP-KO data same as in Figure 2). (c) The branching pattern of basal dendrites from APP/APLP2-DKO mice resembles that of APP-KO neurons (Repeated measure ANOVA with Bonferroni multiple comparison test, n.s.) whereas (d) apical dendrites of APP/APLP2-DKO neurons are characterized by an additional branching defect close to the soma (60 μm, 90 μm, 120 μm, 150 μm; Repeated measure ANOVA with Bonferroni multiple comparison test, **p ≤ 0.01, ***p ≤ 0.001). (e, f) Total dendritic complexity (e) and total dendritic length (f) was not affected in APP/APLP2-DKO neurons as compared to neurons from APP-KO mice (Student’s t-test, n.s.; APP-KO: n = 42 neurons/7 mice, APP/APLP2-DKO: n = 37 neurons/6 mice. All values represent mean ± SEM.