Components and functions of the lymphatic and immune system and primary and secondary lymphatic organs. Development and maturation of B and T Cells. http://www.biog1105-1106.org/demos/105/unit7/lymphaticsys.html  I thought that this was a great picture in that it gives a good overview of both the primary and secondary lymph organs as well as a brief description of the role that they play in the lymphatic and immune systems. To be perfectly honest, I've never really given the lymphatic system much thought prior to now (Big Surprise, most people probably never do)! And furthermore, I guess I wasn't really all that sure what it actually was. The lymphatic and immune systems are sort of a jumble of organs that all really belong to another system! Prior to this class, I certainly never thought of bone as playing a part in immunity, yet its marrow is the site where the body produces blood cells including the lymphocytes (T-Cells and B-Cells) that protect our body from invading pathogens through direct cellular and humoral responses. While the B-Cells remain in the bone marrow for maturation, The T-Cells then go on to the Thymus (Hey, isn't that an endocrine organ?) to mature and prepare for battle against invaders. I think that I mentioned on an earlier slide that related to blood that there was so much information on the white blood cells, that I was simply trying to memorize the information. In the chapters on immunity and the lymphatic system, that information all started to make sense.