Xanthippe - one of the fascinating things about the lymph system is lymph circulation, which is dependent on a number of factors including blood pressure, fluid pressure in the tissues surrounding the lymph vessels, gravity, the unique structure of the initial lymphatics (the open end of lymph vessels that sort of vacuums fluid out of tissue spaces), body movement, external pressure within certain specific limits and the unique ability of lymph vessels to contract -- sort of like intestinal peristalsis -- all of which stimulate lymph circulation and move fluids along through the system. Damage to the lymph vessels and nodes -- from infection, injury, surgery and radiation among other things -- creates scar tissue in the lymphatics and the surrounding tissue which blocks lymph circulation and creates stasis or edema around the scarred area, causing lymphedema disease. One of the characteristics of lymphedema disease is the growth of fat cells in the edematous area as well as fibrosis -- or more scar tissue due to constant inflammation of edematous tissues. Scientists are studying how lymph circulates, what things adversely affect lymph circulation, and how tissue changes over time in lymphedema disease. Another problem that scientists are interested in is how cancer cells migrate through the body and lodge in different areas -- often through the lymphatic system.
The article I linked to reviews the difficulty scientists have had of imaging and studying lymph vessels due to their very small size compared to blood vessels. They've learned a lot through all sorts of things like micron photography and through sticking tiny tubes into the vessels to monitor fluid circulation. They've been able to map lymph circulation in a very detailed way, but there are limits to those methods. However now due to bioengineering they can construct sample lymph systems "from the ground up" in the test tube and study it that way, as well as studying the lymph system in the living organism.
If that made any sense, let me know. That's my job, condensing this stuff and explaining it to beginners. Effective lymph drainage massage is dependent upon knowing a great deal about lymph circulation and how it is affected by all sorts of factors including touch. Lymph drainage massage is the most scientifically studied form of massage, and the more the student knows about the scientific basis of the massage the more effective they can be.
Besides, lymph circulation is just plain fascinating. A marvel of evolution. People go on about how complex the eye is -- the lymphatic system if fabulously complex and very very interesting. There is a great deal of bullshit taught about lymph drainage massage, which is a pity. I like to make sure students understand the science of it, and it's fun to then bring up some of the bullshit and have them do some critical reasoning about it.
Sorry, late at night, all by myself, and indulging in a little shop talk.