Morphometric dendritic field analysis of pyramidal neurons in the human prefrontal cortex: Relation to section thickness

The 3-dimensional (3D) basal dendritic branching patterns of the layers IIIc and V pyramidal neurons in the human prefrontal cortex were morphometrically analyzed using Golgi-Cox stained single sections without reconstruction. Since the dendritic field extends beyond the section, the section thickness affected its 3D measures, such as total dendritic length per neuron. An exploratory analysis to assess the cutting effect in relation to section thickness was performed by examine the graphic display of the following dendritic measures per section thickness class of 10 mu m, within a total range of 101-210 mu m: (1) percentage cut dendritic segments, (2) individual terminal segment length, (3) radial distance from the terminal tips, and (4) total dendritic length per neuron. Additionally, 1-way analysis of variance (ANOVA) was applied with section thickness as main factor. The graphic displays did not show a trend towards increasing dendritic lengths and distances with increasing section thickness. In general the ANOVA showed no statistically significant effect of section thickness, with the exception of one thickness class (layer IIIc: 151-160 mu m). This leads to the conclusion that the thickness range has to be larger to detect a cutting effect related to section thickness.