Fig. 3

TMPRSS2 staining in cross and longitudinal sections of plucked and skin-embedded human HF. Single TMPRSS2 (green) staining in a longitudinal section (A) of skin-embedded HF showing strong signal in the outermost cell layer of the papillary region adjacent to the dermal sheath and weaker expression within the outer root sheath (ORS). Co-staining of TMPRSS2 (green) with the ORS marker KRT15 (red) in a longitudinal section (B) confirms TMPRSS2 localization in the basal and suprabasal layers of the ORS. Double labeling of TMPRSS2 (green) with the companion-layer marker KRT6/75 (red) allows clear distinction between ORS and inner root sheath (IRS) compartments (C). Magnified view (C’) of the boxed area in (C) highlighting partial overlap of TMPRSS2 and KRT6/75 signals at the interface between the ORS and the companion layer (CP) as well as the orientation relative to the epidermis. Cross section (D) showing TMPRSS2 expression in the ORS and Henle’s layer (He) of the IRS. Cross section co-stained for TMPRSS2 (green) and KRT15 (red) confirming TMPRSS2 localization in the basal ORS (E). Cross section (F) co-stained for TMPRSS2 (green) and KRT6/75 (red) delineating the boundary between TMPRSS2-positive ORS cells and the companion layer with partial overlap at the interface. (Nuclear marker DAPI is shown in blue. Scale bars: 100 μm (B,C), 50 μm (A,D–F).