COMPARISON OF LYMPHATIC VESSEL LABELLING METHODS

Objective To compare different lymphatic vessel markers and labelling methods in order to find an ideal way for studying lymphangiogenesis in tumors. Methods Thirty normal gastrointestinal tissues were stained with 5′-Nase.The expression of VEGFR-3 and Podoplanin in 30 paraffin-embedded samples were examined using immunohistochemistry technique. Results Lymphatic vessel density(LVD) was different with different staining methods: The LVD of VEGFR-3 group(14.33±2.24) was significantly higher than that of 5′-Nase group(6.78±1.16) and podoplanin group(6.85±0.84)(t=7.55,7.49;P0.01).There was no significant difference between 5′-Nase and podoplanin groups(t=0.07,P0.05).Lymphatics positively stained by 5′-Nase and podoplanin were found in lamina propria and submucosa.The lymphatic walls were thinner and no red blood cells were found within lymphatics.VEGFR-3 positively stained lymphatics were also found in lamina propria and submucosa.Part of the lymphatic walls were thicker,and red blood cells were found in the lymphtic duct.There was a clear background after podoplanin and VEGFR-3 staining,which clearly showed the relationship between the lymphatics and the surrounding tissue,while 5′-Nase staining showed wheat color background,which obscured the surrounding tissue structure of the lymphatics. Conclusion Immunohistochemistry staining with podoplanin was an ideal method for labeling tissue lymphatics.