Fig. 5

Representative images from control (a, e) and COVID-19 (b–d, f–h) retinal sections, immunolabeled with Iba1 (red) and collagen type IV (blue) to detect microglia migration towards the vessels. a–d, a’–d’ Most of the microglia cells in COVID-19 patients were found surrounding the vessels compared to controls (a vs. b–d). e–h Flat-mount retinas at the outer plexiform layer showing greater migration of microglial cells toward retinal vessels in COVID-19 patients (f–h) compared to controls. e’-h’ Note not only the migration process but also the morphological changes of the microglial cells due to their activation in COVID-19 patients compared to healthy one (f’–h’ vs. e’). OPL, outer plexiform layer; IPL, inner plexiform layer; GCL, ganglion cell layer; Iba1, ionized calcium binding adaptor molecule 1; Col IV, collagen type IV; Scale bars: 50 µm