lymphoid system

Lymphoid system
Dr. Baha, Hamdi AI-Amiedi
Ph. D .Microbiology
Lymphoid component: The Lymphoid component consist of primary and secondary Lymphoid organs. The primary Lymphoid organs consist of Thymus, Bone marrow and Bursa of fabricious while the secondary Lymphoid organs consist of Spleen &lymph nodes
Lymphoid System organs:
l- primary lymphoid organs
. 1-Thymus
2-Bursa
2-Secoundary lymphoid organs
1-Spleen
. 2-lymph Nodes

Thymus: It is so- called because shape it resemble the leaf of thymus plant .each lobe can be seen divide by septa of connective tissue into series of lobular sub - compartments the outer region of densely packed and rapidly dividing lymphocyte called cortex the central area of more loosely arrange of lymphoid and reticular cell called medulla lymphocytes differentiation in thymus are called T- cell Bursa: it is epithelial & lymphoid organ that is found only in bird it is very similar to the thymus it is composed of numerous lobes each which has cortical and medullar area. The medullar and the cortical regions are separated by layer of epithelial cells. Bursa play role in birds in differentiation of B- lymphocytes.In mammals the Bursa equivalent is not known. It is suggested that bone marrow may do this function