Incorporation of bone marrow-derived cells in tumor lymphatic vessels. High-resolution confocal microscopic analysis was used to show colocalization of EGFP (green) and LYVE-1 (blue) overlapping signals of lymphatic vessels at the surface of tumor tissues. EGFP⁺ cells overlapping with LYVE-1 signals were marked with numbers (1 to 3) and arrows (A-K). Schematic diagram demonstrating possible mechanisms of bone marrow-differentiated CEPCs in the participation of lymphangiogenesis. The bone marrow cells have to be extravagated from the blood vessels and incorporated into the newly formed lymphatics (L). Images in panels A-K were captured with a 10 ×/0.3 NA Plan Neofluar objective lens.