Fig. 5

Appearance of ocular microglia in recipients of B6 or nee lymphocytes. a Iba1 immunostained microglia in the whole mounted retina of an age-matched naïve control mouse depicting quiescent, ramified microglia. Retinal microglia in recipients of (b) CD19⁺ and (c) CD3⁺ cells donated from B6 mice appear uniformly ramified 28 days after transfer. d Horizontal sections of the optic nerve also did not reveal signs of microglial activation. Here the optic nerve of a recipient after adoptive transfer of B6 CD19⁺ cell fraction is shown. Numerous activated microglia are readily identified in recipients of (e) CD19⁺ or (f) CD3⁺ lymphocytes from nee donor mice (bottom row). Both early-stage microglial activation, indicated by hypertrophic somatic areas (arrows in f), and highly activated microglia (arrowhead in e) were observed. g Interactions between transferred T-lymphocytes and activated resident microglia are occasionally found. These cells are located outside the retinal vasculature (V) and are accompanied by additional, unidentified, DAPI positive endogenous cells. h Microglial activation was not observed in the optic nerve of any recipients. Scale bars in a-c, e-f is 50 μm and in d, h 20 μm