Lymphatic valves are present in human dermis. (A) UMAP plot of skin and adipose tissue combined showing the proportion (in %) of valves in each tissue type (skin and adipose tissue). (B) Cleared and immunostained biopsy of whole-thickness human dermis imaged by light-sheet microscopy, showing the presence of condensed PROX1⁺ areas representing lymphatic valves (depicted by arrows). Scale bar: 100 µm. (C) Cleared and immunostained biopsy of human dermis imaged by light-sheet microscopy showing the presence of condensed VE-cadherin regions in valve-like regions (depicted by arrows) of PDPN⁺ LVs. Scale bars: 100 µm. Representative images from n > 7/8 (experiments/donors) (B) and n > 2/4 (experiments/donors) (C) are shown. Source of skin in B and C: abdomen. (D) Whole-mount images of the upper 200 µm of the human dermis showing valve-like structures (depicted by arrows) in PDPN-expressing LVs. Scale bar: 50 µm. (E) Representative images from n = 3 donors showing the colocalization of PROX1⁺FOXC2⁺ LECs in lymphatic valves in the upper 200 µm of human dermis visualized by immunofluorescence of whole mounts. Scale bars: 20 µm. (F and G) Quantification of LEC morphology around lymphatic valve regions. Human skin punches were costained for VE-cadherin and PDPN, and LVs, valves, and LEC shape were visualized in cleared samples by confocal microscopy or light-sheet imaging. LEC shape was assessed in a 60-µm radius (half a circle) spanning the upstream and downstream areas of lymphatic valves. LECs were categorized into three morphological types: oak leaf (OL), cuboidal or mixed (CM), or elongated (EL). (F) Representative images illustrating the different morphological categories. Scale bars: 20 µm. (G) Quantification of LEC shape around valves. A total of 28 valves (50 valve regions) from six donors were analyzed by three independent analyses (D and F). Results are shown as percentages of all valve areas analyzed.