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6. Cells and Tissues of the Immune System Lecture 2 
7. Cells of the Immune System
Tissues/Organs of the Immune System 
8. Cells of the Immune System 
9. Hematopoiesis 
10. Lymphocytes 
12. B Cells
T Cells
NK Cells 
18. Mononuclear Phagocytes
Monocytes and Macrophages
Dendritic Cells 
19. Functions
Phagocytosis
Antigen processing and presentation (APCs)
Activation of T cells 
20. Origin and Development of Macrophages 
22. Dendritic Cells Transport Antigens to L. nodes
Initiation of T Cell Responses 
23. Dendritic Cell Subsets 
26. Lymphoid Organs 
27. Lymphoid Organs 
28. Lymphoid Organs Primary (Generative) Lymphoid Organs
maturation site of lymphoid cells
bone marrow, bursa of Fabricius, thymus, Peyer’s Patches in Pigs and Ruminants Secondary Lymphoid Organs
efficient at trapping and concentrating foreign substances
site of Ag-driven proliferation and differentiation; e.g. Ab production
spleen, lymph nodes, diffuse tissues 
29. Primary Lymphoid Organs 
30. Thymus Site of T cell maturation.
Relative Size
Greatest in Newborn
Absolute Size
Greatest at Puberty
 
33. Effect of Thymectomy in Adult 
34. Bone Marrow Site of hematopoiesis.
Site of B cell maturation in mammals. 
35. Bursa of Fabricius Site of B cell maturation in birds. 
36. Peyer’s Patches Site of B Cell Maturation -Pigs and Ruminants 
 
37. Secondary Lymphoid Organs 
39. Lymph Nodes Local sites of specific immune response.
Strategically placed on lymphatic channels. 
43. Spleen Site of immunological responses against blood-borne Ags.
White pulp rich in lymphoid cells.
Red pulp rich in Macrophages. 
48. Circulation of Naïve and Activated/Memory 
T Lymphocytes