Non-metastatic cervical sentinel lymph nodes in oral melanoma-bearing mice. (A) Detection of a sentinel lymph node (SLN), showing remarkable enlargement, by injection of Evan’s blue dye. In contrast, contralateral LN (CLN) is also stained with dye, but shows no enlargement. (B) Photograph of an enlarged SLN (arrow) on the left side of the cervix and a normal-like CLN (arrowhead). (C) LN weight is significantly increased in nonmetastatic SLNs relative to control, non-draining LNs as determined by t-test. *, P<0.05. Columns, mean; bar, standard error. (D), (E) Light micrographs of hematoxylin and eosin staining in SLNs. At a lower magnification (D), remarkable enlargement of the medulla (Me) is noted. Dilated sinuses (MeS) are clearly visible in the Me of SLNs (E). ALV, afferent lymphatic vessels; SS, subcapsularsinuse; Co, Cortex; LyN, lymphatic nodule; MeC, medullary cord. Scale bars = 50 μm.