ACE2 and COVID-19: ACE2 is encountered in a variety of cells from different human organs (lung alveolar epithelial, small intestinal epithelial, vascular endothelial, smooth muscle cells, brush border cells, cellular cells, parietal epithelial cells, basal epidermal layer of skin, oral and nasal mucosa) and absent in others (lymphoid tissular and hepatobiliary structures) but the role of ACE2-expressing organs do not equally participate in COVID-19 pathophysiology [33,35].