1. Immune system

2. General outline Lymphatic organs: thymus, lymph node, Lymphoid tissue Lymphocyte T ： Th 、 Ts 、 Tc B K NK Macrophage Cells spleen, tonsil

3. Lymphoid tissue:  consists of reticular tissue, macrophage, plasma cell and lymphocyte diffuse L.T.: no border, predominant T cell, postcapillary venules (P.C.V.) lymphoid nodules: clear border, predominant B cells Primary ~Secondary ~ Ag

4. lymphoid tissue

6. Lymphoid organs  Central lymphoid organs Thymus: the generation place of Tc Bone marrow: the generation place of Bc  Peripheral lymphoid organs Contain lymph node, spleen, tonsil The places to proceed immune reactions

7. Thymus  Capsule ( C.T.) interlobular septa  Cortex: Endothelial reticular cell (ERC) Lymphocyte: thymocyte Macrophage: secrete IL-1  Medulla: ERC Lc: few Macrophage: secrete IL-1 Thymic corpuscles Structure:

8. Thymus

10. The cortex of thymus

12. The medulla of thymus

13. Blood-thymus barrier: endothelial cell of continuous capillary very thick basement membrane perivascular space with macrophage in it basement membrane of ERC ERC or their processes with desmosome Prevents circular antigens from reaching the thymic cortex where T cells are being formed Consists of :

14.  the thymic ERC can secrete thymic hormones (thymosin, thymolin, thymopoietin)  induce the stem cell to differentiate into T lymphocyte Thymus function:

16. Lymph node  scattered in the passages of lymph  structure capsule parenchyma Cortex medulla  function Perform immune reaction Filtration of lymph

17. Structure:  capsule: several afferent lymphatic vessels, trabecula  cortex superficial cortex: lymphoid nodule (B) internodule zone primary secondary paracortical zone: diffuse lymphoid tissue(T) cortical lymphatic sinuses subcapsular sinus peritrabecular sinus

18.  Medulla medullary cords: contain many B cells, plasma cells, macrophages medullary sinuses many macrophages

20. Lymph node

21. The cortex of lymph node

23. The medulla of lymph node

25. Recirculation of lymphocytes: Lymphoid tissueEfferent lymphatic vessel P.C.V. Blood circulation

26. Spleen  located in the passages of blood  structure capsule parenchyma white pulp red pulp marginal zone  function immune filter blood to clear out the old red blood cells hemopoiesis blood storage

27. Structure:  capsule: D.C.T. containing smooth muscle; is covered by mesothelium  white pulp periarterial lymphatic sheath: T predominant lymphatic nodules (splenic nodules): B  marginal zone lies between the white pulp and the red pulp

28.  red pulp splenic sinusoid long rod endothelial cells ; gaps between the adjacent cells; no basement membrane; rounded by reticular fibers splenic cord the main components are B, Mφ, etc; is the principle place for filtration of blood

29. Spleen

30. The white pulp of spleen

31. The red pulp of spleen

35. Tonsil  Mucosa Epithelium stratified squamous epithelium form crypts lymphocyte infiltration Lamina propria lymphatic nodules diffuse lymphatic tissue  Capsule: C.T.

36. Tonsil

38. Mononuclear phagocyte system Bone marrow young monocyte Blood monocyte Tissues or organs CT: macrophage Liver: Kuffer cell Lung: dust cell Nerve tissue: microglia Osseous tissue: osteoclast Skin: Langerhans cell

39. Function of MPS:  phagocytosis  participate in immune reaction  secrete bioactive substances