The lymphatic system is derived from the mesoderm germ layer. It includes the spleen and transports lymph from the lower extremities via lymph vessels, nodes, trunks, and ducts to the subclavian vein. The lymphatic system develops from the circulatory system during embryogenesis. Elephantiasis is an infection of the lymph vessels, often caused by the worm Wuchereria bancrofti. The document questions trace the flow of lymph through the body and identify the lymph nodes associated with drainage from different body regions.