a, Schematic images depicting the regions of dorsal mLVs around the transverse sinus. b, c, Representative images and comparisons of the LYVE-1+ area and the diameter of dorsal mLVs around the transverse sinus in young and aged mice. Each dot indicates a value from both sides of the transverse sinus, n = 7 mice per group (LYVE-1+ area around transverse sinus) or a mean value obtained from one mouse, n = 6 mice per group (vessel diameter) from two independent experiments. Mean ± s.d.; P versus young calculated by two-tailed Mann–Whitney U test. n.s., not significant. Scale bars, 500 µm. d, Schematic illustrations depicting the region of basal mLVs around the jugular foramen. e, f, Representative images and comparison of PROX1 fluorescence intensity ratio of valvular LECs to non-valvular LECs of basal mLVs in young (3 months), middle-aged (8–10 months), and aged (24–27 months) mice. White dashed lines demarcate basal mLVs. PROX1 expression is attenuated in lymphatic valve LECs (white arrows) in aged mice. Each dot indicates a value obtained from one mouse and n = 6 mice per group from three independent experiments. Mean ± s.d.; P versus young or middle-aged calculated by two-tailed Mann–Whitney U test. AU, arbitrary unit. Scale bars, 100 µm. g, Schematic diagram of QD705 infusion (1 μl min–1 for 3 min) into the cisterna magna in young, middle-aged, and aged mice and subsequent fluorescence imaging of indicated draining LNs 30 min after the infusion of QD705. h, i, Representative images and comparison of QD705 intensity in mandibular LNs and deep cLNs (outlined with white dashed line) in young, middle-aged, and aged mice. Each dot indicates a value obtained from one mouse and n = 5 mice per group from three independent experiments. Mean ± s.d.; P values versus young or middle-aged calculated by two-tailed Mann–Whitney U test. AU, arbitrary unit. Scale bars, 1 mm. j, k, Representative images and comparisons of the LYVE-1+ LV area in ear skin, tracheal mucosa, and peritoneal side of the diaphragm in young and aged mice. Each dot indicates a mean value obtained from both ears of one mouse, n = 5 mice per group (ear skin), or a mean value obtained from one mouse, n = 4 mice per group (trachea and diaphragm), from two independent experiments. Mean ± s.d.; P values versus young calculated using two-tailed Mann–Whitney U test. n.s., not significant. Scale bars, 250 µm. l–n, Representative images and comparisons of collagen IV, PROX1, or FOXC2 expression in skin dermal LECs of lymphatic valves (white arrowheads) in young and aged mice. Each dot indicates a mean value obtained from one mouse and n = 4 (collagen IV and FOXC2) or n = 5 (PROX1) mice per group from two independent experiments. Mean ± s.d.; P values versus young calculated using two-tailed Mann–Whitney U test. AU, arbitrary unit; n.s., not significant. Scale bars, 200 μm. Source data