3. Discussion The lymphatic system is specialized in the absorption of lymph from the interstitial space, the absorption of dietary lipids from the small intestine, and immune surveillance [64]. Because lymphatic markers were identified much later than blood vessel markers, research in the lymphatic system is quite new compared to that in the blood vasculature. The importance of lymphatic vessels in health and disease is not yet well established. To this end, the work of this thesis was aimed at identifying molecules specifically expressed in lymphatic vessels. In the analysis of transcriptomic data comparing blood and lymph node endothelial cells, CD36 was determined to be specifically upregulated in LECs of HDMECs in the tube formation assay. Therefore, research has been directed at unraveling the role of CD36 in the lymphatic system in vitro and in vivo. In vitro tests showed that CD36 was required for LEC migration and proliferation. Furthermore, the effects of this soluble scavenger receptor were also analyzed in detail structurally and functionally in the skin of CD36-deficient mice and WT littermates. In vivo experiments focused on the skin as cellular experiments focused on dermal LECs. The function of the dermal lymphatic vessels was analyzed in three different tests. In skin absorption experiments, Evans blue and FITC dextran were injected intradermally, and the uptake of lymphatic vessels was visualized. Since these absorption experiments were qualitative, a quantitative test to measure lymphatic function was sought. In a report on hemilin-deficient mice, Evans blue was injected into the paw and the lymph nodes were quantitatively analyzed whether they had the same dye content [167]. However, this test had a window limited to q...... middle of paper ...... of mice treated with anti-VEGFR3 because the lymphatic vessels on the aortic wall were disturbed, underscoring the importance of lymphatic vessels in RCT study [191]. In conclusion, this work highlights important biological aspects of lymphangiogenesis. It also highlights the role of aging on lymphatic function, determined by a new lymphatic absorption test. Furthermore, data from the present thesis show a previously undetermined role of CD36 in adipocyte and lymphatic system biology with a focus on aging assessed using a unique Western diet feeding protocol. Although the findings from a high-fat diet imply that loss of CD36 may improve obesity, this work suggests that such treatment should be carefully considered before implementation. Furthermore, studies involving conditional loss of CD36 in adipocytes of different ages would specifically determine the effects of CD36 loss on metabolism and aging...