Figure 5. ACE2 protein in sinonasal tissues.

Detection of ACE2 protein (brown color, arrows, and insets, a-f) and tissue scoring (g) in representative sections of nasal tissues. a, b) In thick pseudostratified epithelium (PSE) ACE2 protein was absent (a) to rare (b) and apically located on ciliated cells. c) Tissue section shows a transition zone from thick (left side, > ~4 nuclei) to thin (right side, ≤ ~4 nuclei) PSE and ACE2 protein was restricted to the apical surface of the thin PSE. d-f) ACE2 protein was detected multifocally on the apical surface of ciliated cells in varying types of thin PSE, even to simple cuboidal epithelium (f). Bar = 30 μm. g) ACE2 protein detection scores for each subject were higher in thin than thick epithelium, (P=0·05, Mann-Whitney U test). LOD: Limit of detection.