Figure 5.

Invasion of CCR7-B16 cells into CCL21⁺ lymphatic vessels. C57BL6 mice footpad CCR7-B16 tumors were harvested 20 days after inoculation. To statistically assess the difference between lymphatic invasion in CCR7-B16 and control tumors, we stained sections of mouse ear tumors for podoplanin by immunohistochemical methods at day 20 and then counterstained the sections with hematoxylin. Four high-power fields (HPF), which contained the apparent lymphatic vessels in each section, were selected for analysis. The numbers of the lymphatic vessels and tumor cells (identified by hematoxylin staining) that invaded into the lymphatic vessels were counted (See Materials and Methods). Representative results of two tumor samples are shown.