Which of the following is the best explanation for why tumor

Which of the following is the best explanation for why tumors more than 0.2 mm from a blood supply fail to grow? Oxygen cannot effectively diffuse farther than 0.2 mm. Tumor cells grow best in hypoxic conditions. Tumors far from blood supplies must utilize autophagy to provide oxygen. Tumor cells require endothelial cells as a growth surface. Which of the following is true of factors controlling angiogenesis? VEGF is a receptor tyrosine kinase. An unrelated protein, LEGF (lymphatic epithelial growth factor) performs the role of VEGF during lymphangiogenesis. Angiopoictin-1 and -2 control the proportions of endothelial cells, pericytes, and smooth muscle cells during angiogenesis. VEGF was independently discovered and named VIF (vascular impermeability factor) due to its role in preventing vascular leakin Which is a feature of tumor vasculature? Capillaries in tumors tend to collapse due to pressure from the growing tumor. Lymphatic vessels in tumors tend to be leaky. Tumor-associated pericytes are loosely attached to capillaries. Normal vasculature has gaps in the endothelial sheets, visible in electron microscopy, that are absent in tumors.

Solution

question 1: Oxygen can not effectively diffuse farther than 0.2mm

question 2: Third option: Angiopoietin 1 and 2 control the proportions of endothelial cells, pericytes and smooth muscles during angiogenesis.

question 3 : Third Option : Tumor associated pericytes are loosely attached to the capillaries.

Analysis of vascular morphogenesis and pathological angiogenesis suggest that disruption of pericyte contact is required for initiation of angiogenesis.Tight association between endothelial cell and pericyte processes in normal cells.