CNS tissues contain significantly less microglial processes than
tissues. (A) Dorsal columns at the Th1 spinal level were immunolabeled for CD11b and PU.1, and inverted confocal fluorescence images of 12 μm-thick transverse sections are shown in monochrome. Only cross-sectional areas of the dorsal columns are shown. The location of each microglial nucleus positive for PU.1 is indicated by a circle to demonstrate similar distributions of microglia between the Irf8
+/+ and Irf8
-/- dorsal columns, which contrasts to lower densities of CD11b-positive microglial processes in Irf8
-/- mice than in Irf8
+/+ mice. (B) Similar difference was observed in the coronal sections of the corpus callosum. (C) The percentages of CD11b-positive areas in the whole cross-sectional area of the dorsal column were measured and compared quantitatively between Irf8
-/- (closed bar) and Irf8
+/+ mice (open bar). Three 3-month-old animals were used in each genotype. **P < 0.01. Scale bar: 100 μm.