Mechanisms ofvascularization inmurine models ofprimary andmetastatic tumor growth

Directed capillary ingrowth has long been considered synonymous with tumor vascularization. However, the vascu?lature of primary tumors and metastases is not necessarily formed by endothelial cell sprouting; instead, malignant tumors can acquire blood vessels via alternative vascularization mechanisms, such as intussusceptive microvascular growth, vessel co?option, and glomeruloid angiogenesis. Importantly, in response to anti?angiogenic therapies, malig?nant tumors can switch from one vascularization mechanism to another. In this article, we brielfy review the biological features of these mechanisms and discuss on their signiifcance in medical oncology.