Fig. 2

Inflammatory (Iba-1⁺) microglia density in cortex and corpus callosum is regulated by the intestinal microbiota. A Iba-1+ microglia were identified by immunostaining (red), nuclei counterstained with Hoechst (blue), and quantified in the cortex and corpus callosum (highlighted in cartoons) of sagittal mouse brain sections from all groups of mice. B Quantification of Iba-1+ cells in the cortex, average count across 3 regions of interest (ROI) from each of 4–7 mice per group from all groups. C Quantification of Iba-1+ cells in the corpus callosum, an average of 3 regions of interest from each of 4–7 mice per group from all groups. Statistical analysis between the groups of interest by Welch’s t test; error bars denote 95% CI. Significant values are in bold. D Representative immunostaining of Iba-1+ cells in the cortex of young, old, and aged mice, either treated with PBS only, treated with antibiotics only, or with antibiotics followed by FMT from young, old, or aged donors (see also Fig. S1)