Fig. 3: SARS-CoV-2 induces mast cell degranulation in aged chRMs.

Aged chRMs (17- to 19-year old) were anaesthetized by Zoletil 50 and intratracheally inoculated with SARS-CoV-2 (1 × 107 TCID50) in a 2 mL volume by bronchoscope. a Mock infection. The animals were euthanized at 7 dpi (b) or 15 dpi (c, d) and the lung lobes were collected for histology analysis. Toluidine blue staining was used to observe MCs and their degranulation. Red arrow indicates the MCs