The exact histogenesis of high-grade urothelial tumors may be difficult to ascertain in metastatic sites.Clinical information may be of tremendous value in such cases. 如果此高级别尿路上皮肿瘤发生转移，转移灶内瘤细胞的组织发生会很难确定，此时临床病史尤为重要。
VEGF-induced metastatic colonies were surrounded by densely packed stromal cells before detectable angiogenesis, suggesting that VEGF is involved in the initiation of desmoplasia. 在血管形成之前，引入血管内皮生长因子表达的转移灶被高密度的间质细胞包裹，表明血管内皮生长因子参与结缔组织增生的过程。
