Final answer:
The lymphatic vessels, or lymphatics, are responsible for returning fluid that leaks from the vascular system back into the blood, containing lymph nodes that filter and destroy pathogens.
Step-by-step explanation:
The vessels responsible for transporting fluid that leaks from the vascular system back into the blood are the lymphatic vessels or lymphatics. Unlike the cardiovascular system, which includes veins and arteries, the lymphatic system is not a closed circuit and operates in a unidirectional flow. As interstitial fluid, which is fluid that has leaked out of capillaries into the spaces between cells, accumulates, it diffuses into lymphatic capillaries (green in Figure 25.4) and then travels through the lymphatic network. This network includes larger lymphatic vessels and lymph nodes, which filter and destroy pathogens using lymphocytes. Eventually, the lymph is drained back into the bloodstream via the subclavian veins in the upper chest.