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بسم الله الرحمن الرحيم

بسم الله الرحمن الرحيم. LYMPHOID TISSUE. CELLS OF IMMUNE SYSTEM. 1- Lymphocytes: B cells T cells: memory, T H 1 , T H 2 , T C , T S Natural Killer Cells. 2- Plasma cells 3- Mast cells 4- Neutrophils 5- Eosinophils 6- Antigen presenting cells.

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بسم الله الرحمن الرحيم

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  1. بسم الله الرحمن الرحيم LYMPHOID TISSUE

  2. CELLS OF IMMUNESYSTEM 1- Lymphocytes: B cells T cells: memory, TH1, TH2, TC, TS Natural Killer Cells. 2- Plasma cells 3- Mast cells 4- Neutrophils 5- Eosinophils 6- Antigen presenting cells

  3. T-LYMPHOCYTES (زيادة عن المقرر) • Their plasmalemma has: 1- T cell receptors (TCRs). 2- CD molecules or markers ( cluster of differentiation proteins).

  4. T-LYMPHOCYTES (زيادة عن المقرر) • SUBTYPES: 1- Memory cells. 2- T helper cells: Are CD4+ TH1 & TH2 cells 3- T cytotoxic cells (Tc cells) (T killer cells) 4- T suppressor cells ( Ts cells). N.B. Both Tc & Ts cells are CD8+

  5. NULL CELLS (زيادة عن المقرر) 1- Natural killer (NK) cells: are cytotoxic cells. antibody-dependent cell-mediated cytotoxicity. are non-B, non-T cells. are formed in red B.M. no need for maturation in thymus. Kill virally altered cells & tumor cells in non-specific manner. 2- Stem cells.

  6. ANTIGEN PRESENTING CELLS(المطلوب فقط ما تحته خط) 1- B lymphocytes. 2- Macrophages. 3- Dendritic cells: e.g. Follicular dendritic cells, Interdigitating dendritic cells Langerhans cells. 4- Epithelial reticular cells of the thymus. N.B. APCs have class II MHC molecules (MHC II) but other cells have only MHC I

  7. (زيادة عن المقرر) LYMPHOKINES • Are released by: 1- T helper lymphocytes. 2- Antigen presenting cells.

  8. SMALL LYMPHOCYTES (زيادة عن المقرر)

  9. LEUCOCYTES(زيادة عن المقرر)

  10. DEVELOPMENT OF LYMPHOCYTES (زيادة عن المقرر)

  11. TYPES OF IMMUNE RESPONSE (زيادة عن المقرر) • Innate Response:(Fast, non-specific, no memory cells) By: Neutrophils, Macrophages, Mast cells, NK Cells. (2) Adaptive response: a- Humoral immune response b- Cell-mediated immune response

  12. TYPES OF IMMUNE RESPONSE (زيادة عن المقرر) DC: Dendritic cells

  13. LYMPHOID TISSUE

  14. LYMPHOID TISSUE A) Diffuse lymphoid tissue B) Encapsulated lymphoid organs: 1- Lymph nodes. 2- Spleen. 3- Tonsils(are incompletely encapsulated) 4- Thymus. N.B. Both red bone marrow & Thymus are considered 1ry. Lymphoid organs.

  15. DIFFUSE LYMPHOID TISSUE • MALT: lymphocyte infiltration, solitary lymphoid nodules & aggregated lymphoid nodules. - Under the wet epithelial membranes. • Loose C.T is infiltrated with lymphoid cells (lymphocytes, plasma cells, macrophages, reticular cells). - Lymphoid Nodules

  16. LYMPHOID NODULE(LYMPHOID FOLLICLE) • 1ry. : without germinal center • 2ry. : with germinal center

  17. Bronchial-associated lymphoid tissue

  18. LYMPHOID NODULE

  19. LYMPH NODES

  20. LYMPH NODE (L.N.) (A) 1- Capsule 2- Trabeculae (septa) 3- Reticular C.T. • Parenchyma: (lymphoid tissue + lymph sinuses) 1- Cortex 2- Paracortex 3- Medulla

  21. High endothelial venule (postcapillary venule)

  22. CORTEX OF L.N. 1- Lymphatic nodules (follicles): a- 1ry: without germinal center b- 2ry: is formed of: Corona (mantle): Dark, Mostly B-lymphocytes. Germinal center: Lighter, mostly activated B-lymphoblasts with macrophages & dendritic reticular cells. 2- Subcapsular & Cortical (paratrabecular) lymph sinuses.

  23. PARACORTEX Of L.N. • It is the thymus-dependent zone of L.N. • It is composed mostly of T-lymphocytes. • It contains high endothelial vessels (postcapillary venules): - PCV are lined with cuboidal endothelium. - PCV are the site of entry of lymphocytes to L.N.

  24. Medulla of lymph node

  25. Medullary Lymph Sinusoids (Sinuses)

  26. MEDULLA OF L.N. (1) Medullary cords: are formed mainly of lymphoid cells ( B & T lymphocytes, plasma cells, macrophages). (2) Medullary sinusoids ( or medullary sinuses). N.B. Efferent lymphatic vessels drain lymph with B & T lymphocytes.

  27. MAIN CELLS OF L.N. 1- B & T lymphocytes. 2- Plasma cells. 3- Macrophages 4- Dendritic reticular cells

  28. FUNCTIONS OF L.N. • 1- Production of immunocompetent cells. • 2- Filtration of lymph.

  29. SPLEEN

  30. STROMA OF SPLEEN 1- Capsule: is covered by visceral layer of peritoneum; mesothelium. occasionally contains SMCs 2- Trabeculae. 3- Reticular C.T.

  31. PARENCHYMA OF SPLEEN • (A) White pulp. • (B) RED PULP. • (C) Marginal zone. • N.B. No cortex, no medulla. No afferent lymphatic vessel.

  32. Splenic microcirculation

  33. Periarterial lymphatic sheath and the central artery

  34. SPLEEN

  35. Lymphoid nodule with central artery

  36. Lymphoid nodule with central artery

  37. PARENCHYMA OF SPLEEN • White pulp: 1- Periarterial lymphatic sheaths: housing T lymphocytes. 2- Lymphoid nodules ( with germinal centers): housing B lymphocytes. N.B. Both 1&2 have the acentrically located central artery

  38. SPLEEN

  39. Red pulp: • 1) Blood sinusoids • 2) Pulp cords

  40. Blood sinusoids of spleen

  41. (B)Red pulp: 1- Pulp (splenic) cords (of Billroth): Extravasated blood cells, plasma cells, Macrophages & reticular cells and fibers. 2- Blood sinusoids: Are lined with elongated fusiform endothelial cells with large intercellular spaces & supported by discontinuous, hoop-like basement membrane.

  42. (C) Marginal zone: • Between white and red pulps. • Rich in vascular channels (marginal sinuses), especially surrounding the lymphoid nodules • Rich in avidly phagocytic macrophages. • Contains plasma cells, T & B cells, macrophages, interdigitating dendritic cells. • It houses B cells that are specialized to recognize thymic-independent antigens. • Site of first entry of B & T lymphocytes from blood stream to parenchyma of spleen.

  43. FUNCTIONS OF SPLEEN 1- Filtration of blood. 2- Phagocytosis of old RBCs & old blood platelets & invading microorganisms. 3- Production & proliferation of immunocompetent B & T lymphocytes. 4- Production of antibodies.

  44. SPLENIC MICROCIRCULATION 1- Splenic artery 2- Trabecular artery 3- Enter the parenchyma as CENTRAL ARTERY ( in the white pulp) 4- Enter the red pulp as several straight branches named PENICILLAR ARTERIES (pulp arterioles→ Sheathed arterioles→ Terminal arterial capillary) 5- Blood sinusoids 6- Pulp veins 7- Trabecular veins 8- Splenic vein.

  45. Splenic microcirculation

  46. Blood sinusoids of spleen

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