Status of microglia in Ctsk-/- and WT mice. Representative confocal laser scanning micrographs of horizontal sections of the cerebral cortex immunolabeled against Iba1 to detect microglia revealed a pronouncedly increased staining in Ctsk-/- mice as compared to WT (A, B). (C) Fluorescence intensity analysis of sections immunolabeled for Iba1 indicated a significant increase in Iba1 signal in Ctsk-/- mice in the cerebral cortex as compared to WT mice (n = 10 per genotype). Fluorescence intensities were determined as grey value (GV) sums over the entire image, and are given as means ± standard error. (D-F) Representative confocal micrographs of sections immunolabeled against Iba1 revealed that no significant differences were detectable in striatum/mesencephalon, cerebellum or hippocampus of Ctsk-/- animals in comparison to WT. Cx - cerebral cortex; Str - striatum/mesencephalon; Cb - cerebellum; H - hippocampus. Bars - 50 μm. Fluorescence micrographs are displayed in reverse contrast. Levels of significance are denoted as ** for p < 0.01.