Figure 4. Serial histology pictures and micro-distribution of IR700 fluorescence in the tumor 1 h and 1 d after first PIT are shown together with a schema for explaining effectiveness of repeated PIT. Few fluorescent cells in diffuse necrotic cells with micro-hemorrhage are shown 1 h after PIT (Right upper images). Scattered fluorescent micro-clusters of survived tumor cells are shown 1 d after PIT (Left lower images). All cancer cells in clusters (black arrows) are fluoresced (white arrows) that indicate Pan-IR700 homogeneously distributed in survived and proliferated cancer cells.