What is the primary role of collectors in the lymphatic system?

• A. Transport lymph to lymph nodes and lymphatic trunks
• B. Forward lymph to the liver
• C. Connect the superficial and deep lymphatic system
• D. Transfer interstitial fluid to the lymph capillaries

Answer: (A)

Collectors move lymph away from the smallest lymphatic capillaries toward larger vessels, lymph nodes, and onward into the lymphatic trunks. They have valves and smooth muscle in their walls, so they can generate contractions and prevent backflow, ensuring a one-way flow toward immune surveillance in the nodes and toward the thoracic or right lymphatic duct for drainage into the venous system. This transport role is what makes them the primary function of collecting vessels. The other options describe tasks done by different parts of the lymphatic system: absorbing interstitial fluid into capillaries, connecting superficial and deep networks, or routing lymph to the liver, none of which define the main job of collectors.