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Fig. 2 | Eye and Vision

Fig. 2

From: Microglia activation and neuronal alterations in retinas from COVID-19 patients: correlation with clinical parameters

Fig. 2

Vertical section of the retinas from control and COVID-19 patients immunolabeled with ACE2 (ad), CRALBP (eh) and GFAP (il). High magnification of selected area (white squares) allows detection of structural changes throughout the retina in COVID-19 patients compared with the controls (a’, e’, i’ vs. b’–d’, f’–h’, j’–l’). a–d ACE2 protein was mainly present in Müller cells, OS of cones and RPE in both control and COVID-19 retinas. Lack of staining in OS of cones and greater staining at the level of ONL (arrowheads and white dotted areas) and cell body (arrows) was found in some COVID-19 retinas (b–b’, c–c’, d–d’) compared to the controls (a-a’). e–h, e’–h’ Müller cells and RPE stained with antibody against CRALBP in COVID-19 patients showed signs of a disruption of the ELM (arrowheads), disorganization of honeycomb-like pattern and an increase of immunoreactivity in the cell body (arrows). i–l An increase in the staining of astrocytes appears to exist in COVID-19 retinas although differences in the morphology of astrocytes were not clearly observed. Astrocyte protrusion through the ILM was found (k, arrow). Increased reactive gliosis was observed in COVID-19 retinas (j’l’) compared to the controls (i’). Arrowheads show astrocytes in the intermediate and deep capillary plexuses (i, j, l). ACE2, angiotensin-converting enzyme 2; CRALBP, cellular retinaldehyde-binding protein; OS, photoreceptors outer segments; RPE, retinal pigment epithelium; ELM, external limiting membrane; ONL, outer nuclear layer; HFL, Henle fiber layer; OPL, outer plexiform layer; INL, inner nuclear layer; IPL, inner plexiform layer; GCL, ganglion cell layer; ILM, internal limiting membrane; GFAP, glial fibrillary acidic protein; Scale bars: 50 μm

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