The LV network is expanded and displays enhanced drainage in the skin of IL-7 transgenic mice. (A-E) The LYVE-1⁺ lymphatic network in the ear skin of transgenic mice expressing IL-7 in all cells (IL-7tg) or in WT control mice was analyzed in whole mount preparations. (A) Representative images showing LYVE-1⁺ LVs in the ear skin of both genotypes. Scale bar represents 200 μm. (B-E) Image-based morphometric analysis revealed that the average LV diameter (B) and the average LYVE-1⁺ area (C) were significantly increased in ear skin of IL-7tg compared with WT mice. (D) The number of branching points remained unchanged, whereas the average distance between branching points (E) was reduced in IL-7tg compared with WT mice. Results from 1 of 2 similar experiments are shown (n = 4 mice/group). (F-G) To evaluate lymphatic drainage function, Evans blue dye was intradermally injected into the ears of IL-7tg and WT mice and the dye content remaining in the ear was extracted and quantified 16 hours later. (F) Quantification revealed reduced Evans blue levels in the ears of IL-7tg mice, indicative of increased lymphatic drainage. (G) Representative pictures taken 16 hours after Evans blue injection. Pooled data from 3 experiments involving a total of 15-18 mice/group are shown. *P < .05; **P < .01; ***P < .001.