OUBC displays profound increases in sizes of SLN and metastatic spread of cancer cells to SLN. PBS (Control, Co) or 1 × 106 MBT-2 cells (OUBC, Ob) were injected into the urinary bladders of 8-10-week old female C3H mice. 4 weeks after PBS or tumor cell injection, medial iliac lymph nodes (LN) (arrows, A) were harvested as SLN, and photographed (B), and H&E stained (C, scale bars, 100 μm). (D) Comparison of cross-sectional areas of LNs. Graph shows mean ± SD; n = 5 for each group. *p < 0.05 versus Co. (E) Images showing LYVE-1+ LVs, PECAM-1+ BVs, and cytokeratin+ (CytoK+) metastatic cancer cells in LNs. Right panel; high magnification view showing that the CytoK+ metastatic cancer cells congregate closely to the lymph node lymphatic vessels of OUBC. Scale bars, 50 μm. (F) Comparison of LVD and BVD per total sectioned area of LNs. Graph shows mean ± SD; n = 5 for each group. *p < 0.05 versus Co. (G) Comparison of densities of CytoK+ metastatic cancer cells in LNs. Graph shows mean ± SD; n = 5 for each group. *p < 0.05 versus Co.