GFAP-immunostaining in LEW, FIS and WIS rats subjected to nerve injury. The photomicrographs show the effect of a chronic constriction injury (CCI) of the right sciatic nerve on the activation of astrocytes in the dorsal horn of the spinal cord segment L4 at day 21 after surgery in Lewis (LEW; Top), Fischer (FIS; Middle) and Wistar (WIS; Bottom) rats. The number and staining density of GFAP-immunopositive astrocytic cells was enhanced in the right dorsal horn (side of CCI) compared to the left unaffected side in all three strains. Significant differences between strains were not observed. Scale bars: 100 μm.