[Vasculogenesis and angiogenesis]

Vasculogenesis is defined as a neovascularization manner by which endothelial progenitor cells are successively incorporated into the growing capillaries, whereas angiogenesis is another neovascularization manner which includes mitotic proliferations of endothelial cells of the preexisting capillaries and their migration to the vascular tips forming so called "vascular sprouts" or "endothelial buds". Although angiogenesis had been considered to be more prevalent during organogenesis as well as during a wound healing process of adult mammals, recent findings that endothelial progenitor cells were isolated from human peripheral blood and incorporated into sites of active neovascularization have led many researchers to recognize the significance of vasculogenesis in a phenomenon of neovascularization. This paper mainly deals with the history of morphological approaches to clarify the crucial roles of vasculogenesis during organogenesis and a wound healing process.