Figure 1

A) Phase contrast image of a confluent murine primary cortical mixed glial culture. A monolayer of type-I astrocytes is observed with some refringent microglia-looking cells. This image could suggest that this is an almost pure astroglial culture. B) GFAP immunostaining of the same field in A seems to confirm this impression. It is difficult to count how many astrocytes are in the field but since the whole field is covered by astrocytes one might conclude that indeed this is an almost pure astroglial culture. C) Immunostaining with the microglial marker CD11b reveals the presence of numerous (20) microglial cells in the field. These are mainly not the round refringent microglial cells typically recovered by shaking and found on top of the astrocytes. Instead these are more ramified cells, in direct contact with the bottom of the well, between the astrocytes or below them. D) Hoechst staining allows the easy quantification of the total number of cells in a culture. In this field there are 109 cells and microglial cells represent 18%. Hoechst 33258 staining also reveals the different nuclear morphology of astrocytes and microglia. Bar, 100 μm