We are interested in the morphogenetic processes that shape and maintain the vascular systems. We focus especially on lymphatic vessels, during development but also in healthy and diseased adult life. Uptake of interstitial fluid, antigens and cells is achieved by permeable lymph vessels, organized into a network of blind-ended capillaries draining into collecting vessels (Alitalo 2011, Schulte-Merker 2011). Re-circulation of lymph into the bloodstream and filtration via lymph nodes plays a key role in tissue homeostasis, immune reactions, but also in pathologies such as cancer metastasis, cardiovascular- and inflammatory diseases. Functional imbalances in either drainage or re-circulation can lead to lymphedema or ascites (Alitalo 2011). The high permeability of lymphatic capillaries is achieved by oak-leaf shaped endothelial cells, which display discontinuous, “button-like” accumulations of VE-cadherin (Baluk et al., 2007). We will assess in gene-deleted mice, cells and by biochemical analysis the importance of VE-cadherin for the maintenance of LEC junctions, their remodelling into the unique button type junctions and for the stability of lymph vessels. This investigation at different stages of lymph vessel development will help us to identify mechanisms at the dynamic cell-cell or cell-matrix interface, that shape LEC behaviour and thereby the lymphatic vessel system.