LYMPHOID TISSUE Highly vascular, with the framework o connective reticular fibers either encapsulated fully, partially or not capsulated. Cells diffusely aggregated clustered in nodules (follicles) with or without germinal centers. Major cells, lymphocytes B and T with sub populations of plasma cells and macrophages. B lymphocyte formed in bone marrow in mammals and in bursa of fabricius in birds. it is small round with heterochromic nucleus surrounded by small rim of cytoplasm. T lymphocytes formed in bone marrow and migrated to thymus LYMPHOID TISSUE divided into: 1. Nodular lymphoid tissue (lymph nodes, thymus, spleen and tonsils). 2. Diffused lymphoid tissue. Dr.dhyaa

the area between cortex and medulla that populated with T lymphocytes A-Lymph node it is filter lymph including removal of invading microorganisms and various foreign materials, it is oval encapsulated having both efferent and afferent lymphatic vessels and hilus, the afferents lymphatic vessels penetrating the capsule , it has three regions1. Cortex: peripherally of lymph node covered with capsule and its trabeculae and the cortical parenchyma containing spherical shaped lymphatic nodules and diffused lymphatic tissue, these nodules divided into primary and secondary. Each nodule consisted from lymphocytes. Para cortex: the area between cortex and medulla that populated with T lymphocytes Medulla: inner most portion of lymph node that lying near the hilus; it is loosely populated with lymphocyte, plasma cells, macrophages and lymphatic sinuses Dr.dhyaa

Lymph node Dr.dhyaa

Dr.dhyaa