Fig. 3

Histopathology of COVID-19 patient lung tissue reveals loss of extracellular matrix and prominent infiltration of immune cells. A Movat pentachrome stain of lung tissue slices from COVID-19 patients. a–e 20 × images, b 10 × overview. Whilst overall tissue structure is still well defined, none stained positive for collagen and reticular fibres. B a 10 × overview, b–f 20 × images of healthy lung tissue controls. Except f all of the healthy controls display a strong positive staining result (brownish yellow) for collagen and reticular fibres. The reduced signal in f could be explained by an incidental focal inflammation. C a–f 20 × images of H&E stains of COVID-19 samples. Samples display a varying amount of infiltrated immune cells, from minor, early onset inflammation (a, b, f) to advanced inflammation (d, e) to alveoli filled with infiltrate (c). D a–f 20 × images H&E stains of healthy control patients display clinically unremarkable lung parenchyma. Displayed images are representatives of 10 pictures taken per each of the six COVID-19 and control patient analysed in this study