FIGURE 33.

Probing for length and surface in isotropic 0.2 μm semithin sections of Epon‐embedded, toluidine blue stained mouse neocortex. (a) A counting frame used to define a sample of the area and to count intersections of capillaries with the plane of the section in this area. The three capillaries labeled with green arrows can be counted. The capillary marked with the red arrow crosses the exclusion line of the counting frame and is not counted. An additional capillary is labeled with a white arrow. (b) Merz test lines are used to count intersections of the lines with the surface of cortical nuclei. The area to which the lines are applied is again defined by a counting frame. Straight lines could also be used, but the hemicircles composing the Merz lines may be more efficient if the surfaces to be estimated have a preferred orientation in the section (Merz, 1967). Eleven intersections of the lines and the boundaries of nuclei are counted (green arrows). Scale bars: 10 μm [Color figure can be viewed at wileyonlinelibrary.com]