Editing Lymphatic system (section)

====Bone marrow====
{{Main|Bone marrow}}
Bone marrow is responsible for both the creation of [[T cell]] precursors and the production and maturation of [[B cell]]s, which are important cell types of the immune system. From the bone marrow, B cells immediately join the circulatory system and travel to secondary lymphoid organs in search of pathogens. T cells, on the other hand, travel from the bone marrow to the thymus, where they develop further and mature. Mature T cells then join B cells in search of pathogens. The other 95% of T cells begin a process of [[apoptosis]], a form of [[programmed cell death]]: T cells which cannot interact strongly enough with self-antigens are eliminated during {{section link|T_cell#Positive_selection}} while T cells that attack the body's own proteins are eliminated during {{section link|T_cell#Negative_selection}}.