How are lymphatic collecting vessels different from veins?
Lymphatic collecting ducts carry lymph under higher pressure than similarly sized veins carry blood.
Lymphatic collecting vessels contain more valves than do veins.
Lymphatic collecting vessels are composed of tunica externa and tunica intima, whereas veins are composed of tunica intima, tunica media, and tunica externa.
Lymph in lymphatic collecting vessels is propelled by contraction of skeletal muscles.