Electron Microscopic Findings.
SARS-CoV-2 particles were detected within type II pneumocytes, which showed degenerating features characterized by fine and uniformly dispersed chromatin. These pneumocytes displayed swollen mitochondrial profiles and dilated rough endoplasmic reticulum (Figure 3). Numerous virus-containing compartments (VCC) of different sizes and shapes were detected (Figure 3A, 3B, and 3D). Interestingly, spherules, very small vesicles containing single viral particles (Figure 3B and 3C), were also observed.
Figure 3.  SARS-CoV-2 detection in lung tissue by transmission electron microscopy. A, SARS-CoV-2 particles are visible in virus-containing compartments in type II pneumocytes (arrows). B–D, Numerous viral particles are enclosed in single-membrane vacuoles (arrow). Other, very small vesicles contain single viral particles (arrowheads). Scale bars: A, 1 µm; B–D, 200nm.