Fig. 1.

Potential mechanisms of glioma angiogenesis. Currently, (1) sprouting angiogenesis, (2) vascular co-option, (3) vascular intussusecption, (4) vasculogenic mimicry, (5) bone marrow-derived vasculogenesis, (6) cancer stem-like cell derived vasculogenesis and (7) myeloid cell-driven angiogenesis are all considered to contribute to tumor angiogenesis. However, some of these mechanisms have initially been described in developmental angiogenesis and their relative contribution and relevance in human brain cancer is unclear (see text)