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. 2022 Sep 13;13:957224. doi: 10.3389/fimmu.2022.957224

Figure 1.

Figure 1

Distribution and basal expression of the SARS-CoV-2 receptors in healthy placentae. (A) Representative microphotographs showing ACE2, TMPRSS2 and CD147 distribution in placental tissues. ACE2 was localized within syncytiotrophoblasts, whilst TMPRSS2 staining was almost negative. Staining for CD147 indicated a high protein expression. AEC chromogen (red) was used to visualize the binding of anti-human primary antibodies. Red arrows indicate syncytiotrophoblast, blue arrows villous vessels and green arrows show leukocytes in the intervillous space. Nuclei were counterstained in blue with Mayer's Hematoxylin; scale bars, 100 µm. (B) Analysis of mRNA expression of SARS-CoV-2 receptors in placental tissues derived from healthy placentae: 5 from first trimester (grey histograms) and 3 from third trimester placentae. Data are represented as mean ± SE of three independent experiments performed in triplicate. (C) Histograms representing ACE2, TMPRSS2 and CD147 mRNA expression in extravillous trophoblast (EVT), endothelial (DEC) and stromal (DSC) cells isolated from normal first trimester decidua. Data are represented as mean ± SE of three independent experiments performed in triplicate.