Injury induces an early up-regulation of pSTAT3 in astrocytes of the glial lamina. (A–AA) Longitudinal sections of the optic nerve head from the different mouse strains and injuries stained for pSTAT3 (arrows). (E’) An enlargement from E showing colocalization of pSTAT3 with GFAP-labeled astrocytes. At no time after injury was there pSTAT3 labeling in GFAP-STAT3-CKO mice (not depicted). Each panel represents a typical finding from a sample of three to five mice. Bars: (A–AA, except E’) 50 µm; (E’) 10 µm.