Fig. 1: Stromal cell topology in human palatine tonsils.

a–g, Representative immunofluorescence images of palatine tonsil sections from adult patients with OSA stained with the indicated antibodies and analyzed by confocal microscopy. a, Transition zone from the surface to the crypt epithelium. Stratified squamous epithelial cells at the surface (arrows) and UEA1⁺ epithelial cells infiltrated with CD3⁺ lymphocytes (arrowheads) at the transition area to the crypt epithelium are highlighted. DAPI, 4,6-diamidino-2-phenylindole. b, High-resolution analysis of the non-keratinized stratified squamous surface epithelium. PDPN-expressing basal cuboidal epithelial cells are highlighted (arrowheads). c, Morphology of the lymphoreticular crypt epithelium. Broadened PDPN-expressing basal layer of the crypt epithelium (arrows) and papillary extension providing access for blood vessels (asterisk) are highlighted. d, Epithelial and subepithelial (arrowheads) areas underpinned by PDPN⁺ stromal cells. Boxed area shows the magnified epithelial–lymphoid tissue interface. e, B cell follicles with GCs and mantle zones (MZ) underpinned by PDPN⁺ FRCs. f, CD3⁺ lymphocytes in epithelial, GC (asterisk) and interfollicular T cell (arrowhead) areas. g, T cell area surrounding B cell follicles (Fo) underpinned by PDPN⁺ FRCs (arrowhead) and ACTA2⁺PDPN⁻ VSMCs (arrow). Square boxes show cell networks at higher magnification, and rectangular boxes indicate the regions of PDPN- and ACTA2-intensity measurements shown in h. h, Average pixel intensity of ACTA2 and PDPN signal-intensity measurements. The x axis represents the horizontal distance through the selection (rectangular boxes in g), and the y axis represents the vertically averaged pixel intensity. The arrow highlights ACTA2⁺PDPN⁺ myofibroblasts in the perivascular space. Microscopy images are representative for n = 3 adult patients with OSA.