For years, scientists largely ignored the lymphatic system, instead focusing on blood vessels and their growth process, called angiogenesis. Only since the mid-1990s has knowledge started to accumulate about the lymphatic system, the network of thin-walled capillaries that collect and drain used tissue fluids, macromolecules, and cells, sending them to the lymph nodes where they are filtered before returning to circulation. Many have suggested that lymphangiogenesis also may accompany tumor growth and may facilitate tumor metastasis to lymph nodes, but the connection proved elusive.
Since the last decade, new tools and techniques that distinguish lymphatic cells and vessels from those for blood have energized the field. The early results from these advances appear in this issue's Hot Papers.1-3
Independently, groups from the Ludwig Institute for Cancer Research in Victoria, Australia, and from the Massachusetts General Hospital introduced tumor cells into immunocompromised mice. By adjusting the levels of two vascular endothelial ...
