Figure 3. Use of immunohistochemistry and electron microscopy to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in formalin-fixed paraffin embedded (FFPE) autopsy tissues. A) Immunostaining (arrows) of SARS-CoV-2 in the epithelial cells of the trachea. Scale bar indicates 20 µm. B) Ultrastructural features of extracellular SARS-CoV-2 particles (arrow) in association with ciliated cells of the trachea from paraffin section in panel A, prepared using an FFPE on-slide method. Scale bar indicates 200 nm. C) Thin section of a biopsy punch from the original FFPE block in panel A showing viral particles (arrow) ≈75 nm. Scale bar indicates 200 nm.