Abstract / Description of output
Understanding the physiology and immunology of the lymphoid system is handicapped without knowledge of its basic structure. Lymphomyeloid tissues develop from epithelial (bursa of Fabricius and thymus) or mesenchymal (spleen, lymph nodes and bone marrow) anlages which are colonized by blood-borne haematopoietic cells. In the case of central lymphoid organs, haematopoietic stem cells enter the bursal or thymic anlages and develop to become immunologically competent B and T cells, respectively. Hence, B and T cells are of extrinsic origin, as proposed by 70 and 71 and described in more detail in Chapter 3.