Figure 2

Microglial responses to LPS application. Coronal sections of motor cortex, immunoreacted with OX42 antibody to visualise microglia/macrophages 3 days (Figs 2a, b), 7 days (Figs 2c, d) and 2 weeks (Figs 2e, f) after unilateral application of LPS to the pial surface (Figs 2b, d, f) or sham operations on the contralateral (contra), control side (Figs 2a, c, e). Here and in all other figures, the pial surface is at the top and all sections are photographed immediately below the craniotomy, with the same exposure for all pairs of images taken at each survival time. Microglia from layer V are illustrated at higher magnification in the insets. Note that microglia are present throughout the full depth of cortex at all time points and are ramified in the control but are rounded and amoeboid and more numerous in the LPS-treated cortical tissue 3 days and 7 days after LPS application. The numerous immunoreactive cells at the pial surface on both sides of the brain (Figs 2a, b) are likely to be macrophages of haematogenous origin induced by local damage due to craniotomy. Note the reduction in number of such cells at 7 days and that very few remain at two weeks. Scale bar in Fig. 2a = 200 μm and also applies to Fig. 2b; scale bar in Fig. 2c = 200 μm and also applies to Figs 2d – f (Figs 2a and b are of greater magnification than Figs. 2c – f); scale bar in the inset to Fig. 2a = 50 μm and applies to all insets.