Fig. 2: Postnatal genetic deletion of Vegfr2 leads to selection of LECs retaining VEGFR2 expression in dermal lymphatic capillaries.

a Whole mount immunofluorescence of postnatal ears showing the development of dermal lymphatic capillary plexus in the dorsal ear skin. Note the presence of a primary plexus at birth with first capillary sprouts appearing at P3 (arrow) and extending to form a superficial plexus at P6 (arrows). V, ventral side; D, dorsal side. b Genetic constructs for LEC-specific Vegfr2 deletion and tracing. c Experimental scheme for assessing the effect of early postnatal deletion of Vegfr2 (top) on dermal lymphatic vasculature of the ear, analyzed by whole mount immunofluorescence at 5 weeks of age (below). GFP expression indicates efficient Cre recombination in both Vegfr2-deficient (flox/-) and heterozygous control (flox/+) mice, and no vascular phenotype in the mutant. Note efficient depletion of VEGFR2 protein in the collecting vessels (Col, arrows), but not in the distal capillaries (Cap, arrowheads) in mutant mice. d Experimental scheme for assessing the effect of continuous postnatal deletion of Vegfr2 (top) on dermal lymphatic vasculature of the ear, analyzed by whole mount immunofluorescence at 3 weeks of age (below). Note that the extended tamoxifen administration regime is not sufficient to lead to efficient depletion of VEGFR2 protein in all distal capillaries (Cap, arrowheads), unlike in the collecting vessels (Col, arrows), in mutant mice. Boxed areas in (c, d) are magnified. Dotted lines in VEGFR2 staining in (c, d) indicate the outline of collecting vessels. e, f Proportion of VEGFR2⁺ lymphatic capillary ends in ears after early (e) or continuous (f) postnatal deletion of Vegfr2, represented as mean ± s.d. (n = 4-6 mice per genotype as indicated below h). Number of terminal lymphatic capillary ends (g) and branch points (h) in ears after continuous postnatal Vegfr2 deletion, represented as mean ± s.d. (n = 4-5 mice per genotype as indicated). In (e), *p < 0.05; Two-sided Mann-Whitney U test, (f–h), ****p < 0.0001; One-way ANOVA followed by Tukey’s multiple comparison test. Scale bar: 500 µm (a), 250 µm (a, cross sections; c, d).