Evans Blue lymphography identifies tumor blockade of lymph drainage. a). Blue dye injected subcutaneously into the tail base drains into both ING LNs (black dotted circles). However, blue dye does not appear in the AX LN on the tumor-draining side, while it does appear in the AX LN on the normal contralateral side as expected (white dotted circles surround AX LNs). Dotted black boxes show regions shown at higher power in b-e. b). normal contralateral AX LN filled with blue dye. c). Tumor-draining AX LN fails to take up dye. d). Dye appears in normal contralateral ING LN and draining SE lymphatic vessel. e). Dye appears in tumor-draining lNG LN but not in draining SE lymphatic vessel.