FIG 2.

In situ hybridization for the expression of ACE2 and TMPRSS2 mRNA in human placental villi. Paraffin-embedded human placental villi sections were processed as detailed in Materials and Methods. RNAscope probes targeting ACE2 (A), TMPRSS2 (B), or control probe (C) were used according to the manufacturer’s instructions. The hybridized probe signal was amplified using the preamplifier reagent followed by the addition of Opal fluorophores. Both ACE2 (A) and TMPRSS2 (B) show notable punctae (white arrow) in the outermost syncytiotrophoblast layer of the placental villi, compared to the negative control (C). The panels on the right are a magnification of the white squares in panels A to C. The panels represent three independent experiments. Bars, 20 μm.