(A) Representative time-lapse recording of a retinal microglial cell from a young animal, demonstrating dynamic structural plasticity in ramified process. Higher magnification images (inset) of an individual process, taken 80s apart, demonstrate continuous process extensions, retractions, additions, and eliminations. A colorized subtraction image of time-lapse images highlights simultaneous process additions and extensions (in green) and process retractions and eliminations (in red) across a 10-min interval in a representative young retinal microglia cell (B). Positive and negative structural changes were balanced across the dendritic arbor to maintain stable dendritic size, complexity, and symmetry. In aged animals, a qualitatively similar pattern of structural changes in the processes of retinal microglia were found (C, D). (E) Quantitative comparison of process motility in individual retinal microglia located in the inner plexiform layer (IPL) and outer plexiform layer (OPL) of young (n = 42 cells from 4 animals) and aged (n = 49 cells from 4 animals) mice however revealed that mean process motilities were significantly greater in microglia located in the IPL compared to those located in the OPL for both young and aged retina. Comparing young with aged microglia, process motility in aged microglia in the IPL was slightly but not significantly lower, while those in the OPL were significantly lower than their counterparts in the young retina. Scale bars = 50 µm.