Chapter 3 Connective tissue

1. Chapter 3 Connective tissue

2. 1.       General features: 1)   small number of cells and large amount of extracellular ground substance 2)  no polarity 3)   all of them originate from mesenchyme -embryonic CT 4) have functions of connection, supporting, protecting, nutrition, defence and repairing

3. mesenchyme ---mesenchymal cell: structure: • stellate in shaped with processes • a large nucleus, with clear nucleoles • slight basophilic cytoplasm function: a.    undifferentiated cell b. multiple developmental potential→CT cell, SM and endothelial cell ---matrix

4. 2.Classification (1) CT in narrow sense means connetive tissue proper which include: loose CT dense CT adipose T reticular tissue

5. (2) CT in wide sense includes : cartilage bone blood

6. 3.Loose connective tissue (areolar tissue) • consists of cells, fiber and ground substance features: have more types of cells and less fibers

7. functions: connection, supporting, defence and repairing

8. Cells:

9. ① fibroblast ---structure: LM: • large,flattened cell with processes- stellate in shaped • Large ovoid pale nucleus - contain more fine chromatin, with clear one or two nucleoli • Weakly basophilic cytoplasm

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

11. 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

12. fibroblast fibroblast fibrocyte fibrocyte

13. ②macrophage ---structure: LM: • Round, ovoid or irregular in shape • have short blunt processes: pseudopodium • Small and dark nucleus • Acidophilic cytoplasm

15. EM: rich in • a.Lysosome（溶酶体） • b.Phagosome: phagocytosis（吞饮作用） • pinosome（吞饮体）: pinocytosis(胞饮作用) • c.Remnant • d.Microfilament and microtubule

16. ---function: a.    Chemotaxis: chemotactic factor b. phagocytosis: (1)Special phagocytosis: recognize bacterium, virus and foreign cell phagocytosis

17. (2)non specialphagocytosis: carbon particles, dust and dead cells

18. c.secretion: lysozyme（溶菌酶）, complement and interleukin-I (IL-1)and interferon(INF) d.antigen presenting function

19. ③plasma cell ---structure: LM: • round or ovoid • Nucleus with more spot-liked heterochromatin which located eccentrically • Basophilic cytoplasm

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

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

22. Basophilic secreting granules: • heparin: an anticoagulant • Histamine: cause cap. permeability↑, cap. leakage to form edema and contraction of SM • Eosinophil chemotactic factor (chemotactic factor: macrophage, leukocytes)

23. Cytoplasm contain: slow reaction substance ---function: to cause allergic reaction

24. ⑤fat cell ---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

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

26. ⑦leukocytes: neutrophil, acidophil and lymphocyte, ect. lymphocyte neutrophil acidophil

27. 2) fibers

28. ①collagenous fiber (white fiber) LM: • 1-20 um in diameter • Belt-liked wave and branch to form a network • Eosinophilic

30. EM: parallel-arranged fibrils Fibril: • 20-200nm in diameter • Have periodic cross striation at 64nm interval

31. ② elastic fiber (yellow fiber) LM: • thinner and less, 0.2-1.0 um • Slight red (HE) branch and form a network EM: • core: elastin-low electron density • Peripheral: microfibril 10-12 nm, electron dense ↑ fibrillin（微纤维蛋白）

32. ③reticular fiber LM: • thin and less,0.2-1.0 um in diameter • Branch to form network • Argyrophilic fiber (silver impregnation method)

33. EM: type III collagen 64nm cross striation ---distribution: reticular tissue connecting portion, e.g. reticular lamina

34. 3) ground substance ---amorphous colloidal substance ---consists of proteoglycan, glycoprotein and tissue fluid

35. 4.Dense connective tissue ---more fiber ---connection and supporting

36. 1) regular DCT: • parallelly-arranged collagenous fibers • tendon cells: special fibroblast wing-liked processes ---distribution: tendons, ligament and cornea

37. 2) irregular DCT: • Fiber arranged in bundles, running in different direction • Fibroblast • less ground substance ---distribution: dermis, sclera and capsule of some organs

38. 5.adipose tissue ---LCT+fat cells ---white fat T: • single fat cell • distribution in subcutaneous tissue, mesenterium ---brown fat T: • fat cell contain many small lipid droplets, • rich in large mitochondria • centrally-located nucleus • rich in cap. • distribution: neonate

40. white fat T brown fat T

41. 6.reticular tissue ---reticular cells: • stellate with processes-form network • round, ovoid and pale nucleus with 1-2 nucleoli • EM: rich in RER ---reticular fiber: connect to form network ---distribution: hemopoietic tissue and lymphatic tissue