The seminal work of Werner Risau in the study of the development of the vascular system.

Werner Risaus work had a decisive impact on defining the overall nature of neovascularization processes during development and had the capability to integrate different directions in the field of endothelial cell biology research. In particular, he had a special interest in understanding the development, differentiation and maintenance of the blood-brain barrier. Risau very successfully propagated the concept that the same factors, such as basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF), which are essential for the formation of blood vessels during embryonic development, also influence pathological angiogenesis during tumor growth. This review is dedicated to a retrospective analysis of the most important contributions of Risaus work in the field of angiogenesis during embryonic development and in post-natal life, in both physiological and pathological conditions.