Figure 2

Irf8 ^-/- CNS tissues contain significantly less microglial processes than Irf8 ^+/+ 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.