Comprised dendritic arbors in ephrinB1 mutant cortical pyramidal cells.

<p><i>A, B.</i> Representative photomicrographs of golgi-cox impregnated S2 pyramidal neurons from <i>EfnB1^Y/+</i> (<i>A</i>) and <i>EfnB1^Y/−</i> (<i>B</i>) cortices. Note the presence of dendritic varicosities on dendrites from <i>EfnB1^Y/−</i> samples (arrows). <i>C.</i> Sholl analysis of the structure of dendritic arbors. Mean number of dendritic intersections of layer II/III cortical pyramidal neurons show a significant decrease in the number of intersections in pyramidal neurons from <i>EfnB1^Y/−</i> cortex at longer distances from the cell soma. Note that majority of dendritic intersections in <i>EfnB1^Y/−</i> cortex were found proximal to the soma, at a distance of ∼20–50 µm compared to <i>EfnB1^Y/+</i> cortex. <i>D.</i> Quantitative analysis of dendritic branch length shows a statistically significant decrease in the branch length of pyramidal neurons from <i>EfnB1^Y/−</i> samples compared to controls (<i>EfnB1^Y/+</i> = 125 µm±7; <i>EfnB1^Y/−</i> = 88 µm±12; p<0.01). <i>E, F.</i> Higher magnified photomicrographs of <i>EfnB1^Y/+</i> (<i>E</i>) and <i>EfnB1^Y/−</i> (<i>F</i>) pyramidal neurons in the S2 field. Note the varicosities in dendrites from <i>EfnB1^Y/−</i> samples. <i>G.</i> Quantitative analysis of the number of morphologically different spines on the basilar tree of cortical layer II/III pyramidal neurons in <i>EfnB1^Y/+</i> and <i>EfnB1^Y/−</i> samples. A significantly higher number of thin spines are observed on neurons from <i>EfnB1^Y/−</i> mice. <i>H.</i> Analysis of the total density of spines along a dendrite showed fewer spines throughout the entire length of the basal dendrites. Each dot represents 4–5 neurons per individual. n = 5/genotype. * p<0.05, **p<0.001.