1. Connective Tissue
LiDongMei

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 Cartilage ※ Bone ※ Blood ※
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. 2.1.1 Cells in loose connective tissue
there are 7 types of cells present in LCT ※ Fibroblast※ Macrophage※ Plasma cell Mast cell Fat cell undifferentiated mesenchymal cell Leukocytes

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 ---structure: LM:
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 function: Membrane bound granules A few Mitochondria A little RER
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 fibers Collagenous fiber Elastic fiber Reticular 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
20-200nm in diameter
formation: Extracellular polymerize
collagen molecule (type I and III) →collagenous fibril → collagenous fiber

37. elastic fiber (yellow fiber) LM: EM： 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. 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. 2.2   Dense connective tissue
---Abundant fibers and few cells
---connection and supporting
Dense regular CT; Dense irregular CT;Elastic CT

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

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

47. 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

51. 2.4 reticular tissue components: Reticular cells reticular fibers
ground substance
distribution:
hemopoietic tissue
lymphatic tissue