Fig. 1.

Neurosphere-derived pure astrocyte cultures contain no contaminating microglia. Mixed glial cultures (MGC) and pure astrocyte cultures (astro) were prepared as described in the Materials and Methods section, and then analyzed for the appearance of microglia, by phase (A), immunocytochemistry (B) or flow cytometry (C). Scale bar = 50 μm. Note that under phase microscopy (A), phase-bright microglia are seen in the MGC, both under control conditions and in the presence of LPS (20 ng/ml), but none are present in the pure astrocyte cultures. Immunocytochemistry (B) demonstrated the presence of many GFAP-positive astrocytes in both the MGC and pure astrocyte cultures, but Mac-1 positive microglia were seen only in the MGC. Flow cytometry (C) confirmed the presence and absence of Mac-1 positive microglia in the MGC and pure astrocyte cultures, respectively.