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6. LAB 9 Immune System -------human defence system

7. OBJECTIVES: 1. Grasp 3 types of lymphatic tissues 2. Grasp the basic structures of lymph node( 淋巴结 ) spleen( 脾 ) and thymus( 胸腺 )

8. REVIEW 复习

9. 1 Composition （组成） : lymphatic organs Immune system lymphatic tissues Immune cells Immune molecules

10. 1. 淋巴小结（ lymphoid nodule ）： Definition: spherical or ovoid structures mainly composed of B C with clear boundaries Classification: primary LN →secondary LN : Composition: cap germinal center: light zone dark zone Function: humoral immunity

11. thymic corpuscle ★ Spherical, Acidophilic structures Composed of concentrically- arranged epithelial reticular cells significance ： unknown Location: composition In medulla

12. Slides 1 Lymph node( 淋巴结 )(HE) 2 Spleen( 脾 ) (HE) 3 Thymus( 胸腺 ) (HE)

13. What we should find Lymph node （淋巴结）： cortex( three structures) medulla( two structures) Spleen （脾） : white pulp ( three structures) red pulp ( two structures) Thymus( 胸腺 ): cortex medulla (thymic corpuscle )

14. 1 common features LO Abundance intensely lymphocytes 2 different arrangement of three types of LT lymph node and spleen thymus DLT LN LC How to recognize LO

15. 1 capsule 2 Parenchyma

16. 1.Lymph node At low power,the lymph nodes is 豆形,covered by capsule.with a dark-staining cortex at the periphery, pale-staining medulla in center. Possesses a depression-the hilum, a region where lymph leaves and blood vessels both arrive and leave. cortex medulla hilum capsule

17. Capsule (connective tissue) superficial cortex cortex paracortical zone cortical sinuses Parenchyma medullary cords medulla medullary sinuses General structure of lymph node

18. 2. Spleen Capsule (CT, serous membrane) splenic corpuscle white pulp peri-arterial lymphatic sheath Parenchyma splenic cords red pulp splenic sinuses marginal zone

19. General structure of thymus Capsule (CT) cortex (periphera region, dark-staining) Parenchyma medulla (central portion (lobules) pale-staining,with Hassall's corpuscles)

20. white pulp : Dense accumulation of lymphocytes 1 periarterial lmyphatic sheath: Tcells 动脉周围淋巴鞘 around central artery 2 splenic corpuscle: lymphatic nodule B:periarterial lymphatic sheath A:spleenic corpuscle A B

21. Red pulp: dark red mass,occupies all the space except capsule and white pulp. 1 Splenic cords: Lymphatic cord with numerous erythrocytes 2 Splenic sinuses: Between splenic cords, composed of rod-shaped endothelial cells filled with blood.

22. test

23. Which organ ？ Which structure? Lymph node Lymphoid nodule

24. Which structure ? which organ? medulla cords medulla sinuses Lymph node

25. which organ? spleen

26. Which structurer? Hassall's corpuscles

27. Which organ? spleen

28. Which organ? spleen

29. Which organ? Lymph node

30. Which structurer? Subcapsular lymphatic sinuses

31. Immune cells: Lymphocytes (T-/B- lymphocytes) Antigen presenting cell Ohters: Plasma cells Granulocytes Mast cells, an so on Mononuclear phagocytic system

33. lymphoid nodule Diffuse lymphatic tissue lymphoid cord

34. Lymphatic organs: Central (or primary) LO: Bone marrow, thymus Peripheral (or secondary) LO: lymph node spleen tonsils

35. cortex hilum capsule medulla

36. Capsule Dense connective tissue, extending into center and form trabecula. Afferent lymphatic vessel- Large, thin-walled, irregular-shaped, collapsed-looking vessels. afferent lymphatic vessel

37. Cortex  superficial cortex  paracortical zone  cortical sinuses

38. superficial cortex- lymphoid nodule Formed mainly by B lymphocyte. stimulated by antigen,the diameter can be much larger and germinal center(pale stained) can easily seen. lymphoid nodules are temporary structures,they may develop, disappear and redevelop. The size and number of nodules vary widely. Germinal center is temporary structure like lymph nodules.

39. Paracortical zone Lies in deep portion of cortex and on the border of medulla.Lies in deep portion of cortex and on the border of medulla. Compose of DLT, mainly with T lymphocyte.Compose of DLT, mainly with T lymphocyte. Postcapillary venules can be seen among them. Postcapillary venules can be seen among them.

40. Postcapillary venules High cuboidal epithelium

41. Subcapsular sinuses: Beneath the capsule Beneath the capsule Lymphatic sinuses Lymphatic sinuses Marcophage,plasma cell Marcophage,plasma cell

42. Medullary sinuses: Irregular space around medullary cords. Medullary cords Densely lymphatic strands.

43. This is the hilum region of a node where lymph leaves via efferent lymphatics and where blood vessels both arrive and leave. hilum

44. Capsule : (compare to lymph node)  Thicker,covered by a serous membrane,  more smooth muscle and elastic fibres.  Enter into parenchyma and form trabeculae.

45. capsule Capsule: DCT, extend into the thymus and subdivid the thymus into lobules.

46. Cortex: Peripheral region, dark-staining, No lymphoid nodules Cortex capsule

47. Hassall's corpuscles (Thymic corpuscle) Medulla: Hassall's corpuscle, with concentric layers of keratinizing epithelial cells. Central cells often show degeneration and nucleus can not be seen.

48. cortex medulla hilum capsule