Ym1 is primarily expressed in alternatively activated microglia during inflammatory response. (a–c) Immunofluorescence staining with antibodies to MAR-CO, GFAP, NeuN, and Ym1 in the hippocampus of p47phox−/− mice, showing that the Ym1+ cells overlaps precisely with MARCO+ microglia. Tissue samples were prepared from brains of p47phox−/− mice at 24 h after LPS. Scale bar, 25 μm.