Excised lymph nodes from rats B and D and contact radiography. Two excised lymph nodes from rat B are shown (A, left). Both lymph nodes were fluorescent (A, center). Contact radiography indicated that the nodes showing increased radioactivity also demonstrated increased levels of fluorescence (A, right). Four excised lymph nodes of rat D are shown (B, left). Two of the four lymph nodes were fluorescent. Fine spatial distribution of the fluorescence was observed in the lymph nodes (B, center). Contact radiography indicated a high level of accumulation of 99mTc in the fluorescent lymph nodes (B, right).