Connective Tissue

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

4. 1.2 Component Cell Connective tissue amorphous Ground substance Extracellular matrix（ECM） Fiber

5. 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

6. 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

8. 1.4 Functions • have functions of connection, supporting, protecting, nutrition, defence and repairing

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

10. 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

11. 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

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

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

15. Synthesis of collagenous fiber in three steps: a. synthesis of procollagen (RER) → process (Golgi) → procollagen → out of cell b. procollagen→ tropocollagen → fibril c. fibril → collagenous fiber

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

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

21. B.secretion: cytokines, growth factors and complement protein. C.antigen presenting function: *capture antigen→processes→+ MHC II molecule (major histocompatibility complex molecules) →antigen-MHC II complexes→T lymphocytes

22. The mononuclear phagocyte system 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

23. Langhans cell

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

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

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

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

29. 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

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

31. ⑦leukocytes: Granulocyte: neutrophil, eosinophil and basophil Agranulocyte: lymphocyte (B, T) monocyte Myofibroblasts, Pigment cells

32. 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

33. Questions: • 1. What kind of cells present in loose connective tissue? And what are the functions of those cells? • 2. What is (are) the structure cell(s) of connective?

34. 2.1.2 fibersCollagenous fiberElastic fiberReticular fiber

35. 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

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

37. elastic fiber (yellow fiber) LM: • thinner and less • Slight red(HE), purple or blue(special stained) • Branch and form a network EM： • core: elastin • Peripheral: microfibril

38. 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

40. 2.1.3 ground substance ---amorphous colloidal substance ---consists of proteoglycan, glycoprotein and tissue fluid

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

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

44. 2.2Dense connective tissue ---Abundant fibers and few cells ---connection and supporting Dense regular CT; Dense irregular CT;Elastic CT

45. 2.2.1 regular DCT: • parallelly-arranged collagenous fibers • tendon cells: /special fibroblast /wing-liked processes distribution: tendons, ligament and cornea

46. 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

47. 2.2.3 Elastic Tissue: • elastic fiber in bundles or in membrane • ligament and large artery

48. 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