Connective Tissue

1. Connective Tissue Website：m-learning.zju.edu.cn LiDongMei may75119@163.com

2. 1. Introduction Connective tissue is versatile，the types including Connective Tissue proper and the specialized Cartilage ，Bone and Blood. Connective tissue comprises a diverse group of cells embedded in a tissue-specific extracellular matrix（ECM）.

3. The capsule also is connective tissue

4. 1.1 Classification • Connective Tissue proper Loose connective tissue ※ Dense connective tissue Adipose tissue Reticular tissue • Cartilage ※ • Bone ※ • Blood ※

5. 1.2 Component Cell Connective tissue Ground substance Extracellular matrix（ECM） Fiber

6. 1.3 Characteristics Have small number of cells but have much extracellular matrix. all of them originate from mesenchyme-embryonic CT have functions of connection, supporting, protecting, nutrition, defence and repairing

7. mesenchymal cell structure: 1)stellate in shaped with processes 2)a large nucleus,with clear nucleoles 3)slight basophilic cytoplasm function: 1) undifferentiated cell 2) multiple developmental potential

9. 1.4 Functions have functions of connection, supporting, protecting, nutrition, defence and repairing

10. 2. Connective tissue proper Loose(areolar) connective tissue※ Dense connective tissue Adipose tissue Reticular tissue

11. 2.1 Loose connective tissue 1) functions: connection, supporting, defence and repairing 2）consists of 7 types of cells, 3 types of fiber and ground substance

12. there are 7 types of cells present in LCT※Fibroblast※Macrophage※Plasma cellMast cellFat cellundifferentiated mesenchymal cell Leukocytes 2.1.1 Cells in loose connective tissue

14. ① fibroblast • ---structure: • LM: • large,flattened cell in shaped • Large ovoid pale nucleus with clear one-two nucleoli • Weakly basophilic

15. EM: rich in RER, Golgi complex and free ribosome ---function: synthesize fibers and ground substance

16. *fibrocyte:still state or inactive fibroblast ---structure: spindle-shaped, small N:small,dark stained Acidophilic cytoplasma EM: less organelles ---function:become into fibroblast for repairing Two stages of activity

18. ②macrophage （The mononuclear phagocyte system） ---structure: LM: round or ovoid-irregular in shape Small and dark nucleus Acidophilic cytoplasm

19. EM: rich in a.lysosome b.Phagosome c.Remnant

20. Function: a. Phagocytosis: Special phagocytosis: recognize Bacterium, virus and foreign cell Non special: carbon particles, dust and dead cells B.secretion: cytokines, growth factors and complement protein. C.antigen presenting function:

21. *capture antigen→processes→+ MHC II molecule (major histocompatibility complex molecules) →antigen-MHC II complexes→T lymphocytes

22. Monocyte in blood is the precursor of macrophages Liver: Kupffer cells Central nervous system: microglial cells Skin: Langhans cells Lymph node: dendritic cells Bone: osteoclast The mononuclear phagocyte system

23. ③plasma cell ---derive from B lymphocyte ---structure: LM: round or ovoid Round eccentrically-located nucleus with more spot-liked heterochromatin Basophilic cytoplasm

24. EM: rich in parallelly arranged RER, free ribosome and Golgi complex ---function: synthesize and secrete antibody（immunoglobulin）

25. ④mast cell ---structure: LM: round and large cell Small dark-stained nucleus Basophilic secreting granules

26. EM Membrane bound granules A few Mitochondria A little RER function: cause allergic reaction

27. ⑤fat cells (adipose cells) ---structure: large, round or polygonal flattened ovoid nucleus located on one side of cell thin layer of cytoplasm a large lipid droplet ---function:synthesize and store fat

28. ⑥undifferentiated mesenchymal cell ---structure:similar to fibrocyte ---function: multidifferentiating potential

29. ⑦leukocytes: Granulocyte: neutrophil, eosinophil and basophil Agranulocyte: lymphocyte (B, T) monocyte

30. Questions: What kind of cells present in loose connective tissue? And what are the functions of those cells?

31. summary A. Classification of CT B. 7 types of cell in LCT 1. fibroblast 2. macrophage 3. plasma 4. mast cell 5. fat cell 6. undifferentiated mesenchymal cells 7. leukocyte

32. 2.1.2 fibersCollagenous fiberElastic fiberReticular fiber

33. Collagenous fiber (white fiber) LM: 1-20 um in diameter Belt-liked wave and branch to form a network Acidophilic are inelastic and have great tensile strength

34. EM: parallel-arranged fibrils Fibril: 20-200nm in diameter formation: Extracellular polymerize collagen molecule (type I and III) →collagenous fibril → collagenous fiber

35. elastic fiber (yellow fiber) LM: thinner and less Slight red(HE), purple or blue(special stained) Branch and form a network

36. reticular fiber LM: thin and less,0.2-1.0 um in diameter Branch to form network black (silver impregnation method) ---distribution: reticular tissue connecting portion, e.g.reticular lamina

38. 2.1.3 ground substance ---amorphous colloidal substance ---consists of proteoglycan, glycoprotein and tissue fluid

40. Function of the ground substance Connection affect the differentiation and movement of cells a barrier to the penetration of foreign particles

41. Summary Loose connective Tissue 3 fibers and 7 kinds of cells

42. 2.2Dense connective tissue ---Abundant fibers and few cells ---connection and supporting Dense regular CT; Dense irregular CT;Elastic CT

43. 2.2.1 regular DCT: parallelly-arranged collagenous fibers tendon cells: /special fibroblast /wing-liked processes distribution: tendons, ligament and cornea

44. 2.2.2 irregular DCT: Fiber arranged in bundles,runing in different direction Fibroblast less ground substance ---distribution: dermis, sclera and capsule of some organs

45. 2.2.3 Elastic Tissue: elastic fiber in bundles or in membrane ligament and large artery

46. 2.3 adipose tissue ---LCT+fat cells ---white fat T: single fat cell ---brown fat T: fat cell contain many small lipid droplets, rich in large mitochondria centrally-located nucleus

49. 2.4reticular tissue components: Reticular cells reticular fibers ground substance distribution: hemopoietic tissue lymphatic tissue

50. Exercise 2 for Histology 1. Compare the structure of microvilli with cilia. 2. What kind of cells present in loose connective tissue?