Fig. 3

Immunofluorescent images of whole-mounted retinas stained for AIF1. Representative nerve fiber layer images of retinas from wild-type and Bax ^−/− mice stained for AIF1 (red label) at 7, 14, and 21 days post-crush. These are representative of the images used to quantify the number of microglia present after crush. a–d In wild-type mice, a baseline resting microglial population was present in the retina. These microglia exhibited small somas with numerous long processes. After crush, the number of microglia increased, and the morphology transitioned to an amoeboid state as the cell somas thickened and the processes retracted. By 21 days, while there was still a prominent population of AIF1-positive microglia, the number of cells was beginning to decline. e–h The number and morphology of microglia in the Bax ^−/− mice contrasted starkly with the population in the wild types. The number of microglia in the knockout mice did not increase by 7 days after crush, and after a modest increase in AIF1 labeling at 14 days, the number of microglia dropped considerably. Interestingly, the morphology of microglia in the Bax ^−/− mice appeared amoeboid, even in the control eyes, characteristic of an early activation state. These microglia exhibited very few processes and thickened somas. Microglial counts were obtained from at least six images, and each image is approximately 0.04 mm². DAPI nuclear counterstain (blue label). Scale bar 50 μm. For each genotype at each time point, n ≥ 3