1. Connective tissue proper
Chapter 3
Connective tissue proper

2. Content Characteristics and classification of connective tissue
Connective tissue proper
Loose connective tissue (cells, fibers)
Dense connective tissue
Adipose tissue
Reticular tissue

3. Introduction Connective tissue (CT) comprises a diverse group
of cells and specific
extracellular matrix.

4. All of CTs originate from mesenchyme embryonic CT
mesenchymal cells

5. Components of CT Cell Connective tissue Ground substance Fiber
Extracellular matrix
Fiber
Tissue fluid

7. Classification of CT A. Connective tissue proper
Loose connective tissue
Dense connective tissue
Reticular tissue
Adipose tissue
B. Specialized connective tissue
Blood
Cartilage
Bone
Lymph

8. A variety of connective tissue

9. Characteristics of connective tissue
A. Have small number of cells but have much
extracellular matrix.
B. The cells in connective tissue have no
polarity, and they are widely separated in
the extracellular matrix.
C. Have no basement membrane, but have
blood vessel and nerve.

10. Function
CT have functions of connecting, supporting, protecting, nutrition, defense and repairing.

11. loose connective tissue
7 types of cells present in LCT Fibroblast, Macrophage, Plasma cell, Mast cell,
Fat cell, undifferentiated mesenchymal cell ,
Leukocytes.
3 types fibers
Collagen fibers, Elastic fibers and Reticular fibers

12. Loose connective tissue

13. Loose connective tissue
Loosely arranged fibers and abundant cells

14. Loose connective tissue3 6
1. fibroblast
2.macrophage
3. mast cell
4. fibrocyte
5. fat cell
6. collagenous
fiber
7. elastic fiber
8. capillary 8 4 2 5 1

15. Fibrocyte----quiescent
Seven types of cells present
in loose connective tissue
① Fibroblast
Fibroblast---active
Fibrocyte----quiescent

16. ① Fibroblast Structure LM: Large,flattened cell stellate in shaped
Large ovoid pale nucleus-contain more
fine chromatin, with clear one-two
nucleoli
Weakly basophilic

17. ① Fibroblast Fibroblast---active EM:
Rich in RER, Golgi appatatus and free ribosome
Fibroblast---active
---Function: synthesize fibers and
ground substance

18. *Fibrocyte: still state or inactive fibroblast
---structure:
LM:
spindle-shaped, small
Nucleus:small,dark stained
Acidophilic cytoplasma
EM: less organelles
---Function: become into fibroblast for repairing

20. ②Macrophage ---structure LM round or ovoid-irregular in shape
Small and dark nucleus
Acidophilic cytoplasm

21. EM: rich in ②Macrophage a. lysosomes b. Phagosomes← phagocytosis and
pinosomes ←pinocytosis
c.  Irregular surface

22. Macrophage-SEM
RBC

23. Macrophages engulf bacteria

24. a. Phagocytosis Function Special phagocytosis: recognize bacterium,
virus and foreign cell
Non special: carbon particles, dust and
dead cells
*Phagosome (pinosome) + primary lysosome
→secondary lysosome →remnants

25. Function B. secretion: lysozyme, complement and
interleukin-I (IL-1)and interferon(INF)
C. antigen presenting function:
*capture antigen→processes→+ MHC II molecule (major histocompatibility complex molecule→antigen-MHC II complexes→T lymphocytes
D. Chemotaxis in inflammatory response

26. 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

27. nucleus ---structure: granules ③ Mast Cell LM: round and large cell
Small dark-stained nucleus
Basophilic secreting granules
nucleus
granules

28. EM
Membrane bound granules
A few Mitochondria
A little RER

29. Basophilic secreting granules:
heparin: an anticoagulant
Histamine : cause cap. permeability↑
Eosinophil chamotactic factor of anaphlaxis (ECF-A)
Cytoplasm contain:
leukotriene - slow reaction substance of
anaphlaxis
---Function: cause allergic reaction

30. --- structure: LM: round or ovoid
④ Plasma cell
--- structure:
LM:
round or ovoid
Round eccentrically-located nucleus with more spot-liked heterochromatin
Basophilic cytoplasm

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

32. Arrows: plasma cells

33. large, round or polygonal
⑤Fat Cell (adipocyte )
---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

34. ⑥Undifferentiated Mesenchymal Cell
---structure:similar to fibrocyte
---function: multidifferentiating potential

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

36. Fibers Collagen fiber Reticular fiber Collagen (19 members)
Elastic fiber Elastin
Collagen (19 members)

37. LM: ①Collagen fibers (white fibers)
Collagen fibers made of collagen type I are the most numerous fibers in CT
LM:
1-20 um in diameter
Belt-liked wave and branch to form a network
Eosinophilic

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

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

41. Formation:
Collagen fibril
Collagen molecule
(tropocollagen)
Collagen (type I,III)
triple helix
α chain (procollagen)

43. Electron micrograph of human collagen fibrils

44. ② Reticular fiber LM: thin, with a diameter between 0.5 and 2.0 um
Branch to form network
Argyrophilic fiber (silver impregnation method)
EM:
type III collagen
64nm cross striation

46. ③ Elastic fiber (yellow fiber)
LM:
thinner and less, um
Slight red (HE), purple (aldehyde fuchsin) or brown (orcein)
Branch and form a network
EM:
core: elastin-low electron density
Peripheral: microfibril nm, electron dense ↑
fibrillin

47. Collagen fiber and Elastic fiber

48. Skin dermis, the elastic fibers are responsible for the skin elasticity.

49. Elastin molecules are joined by covalent bonds to generate an extensive cross-linked network.
Abundant in vertebral ligaments, larynx, and elastic arteries.

50. 2. Ground substance
☻a highly hydrated colorless and transparent complex mixture of macromolecules occupies the space between the cells and fibers.
☻formed mainly of glycosaminoglycans, proteoglycans, and glycoproteins.
☻lubricant, permits O2 and nutrients exchange

52. ①proteoglycan ---glycosaminoglycans: chondroitin sulfate
large molecular complex
---glycosaminoglycans:
chondroitin sulfate
keratin sulfate
dermatan sulfate
heparin sulfate
hyaluronic acid
--protein core

54. Tissue fluid

55. Dense connective tissue
---Abundant fibers and few cells
---Connection and supporting
Dense regular CT
Dense irregular CT

56. (1) irregular DCT:
Fiber arranged in bundles, running in different directions
Fibroblast
less ground substance
Distribution:
dermis, sclera and capsule of some organs

57. Dense irregular connective tissue from human dermis

58. tendon cells /special fibroblast Distribution:
(2) Regular DCT:
parallel-arranged collagen fibers
tendon cells /special fibroblast
Distribution:
tendons, ligament and cornea

59. Longitudinal section of tendon
Cross section of tendon

60. Reticular tissue
reticular cells
reticular fibers
ground substance

61. Distribution: Hemopoietic tissue and lymphatic tissue
Reticular tissue provides the architectural framework that creates a special microenvironment for hematopoietic organs and lymphoid organs.

62. Section of an adrenal cortex, silver stained to show reticular fibers
Section of an adrenal cortex, silver stained to show reticular fibers. This is a thick section made to emphasize the networks formed by these fibers. Nuclei are black, and cytoplasm is unstained.

63. (1)Unilocular (common or yellow) adipose tissue
---LCT+fat cells
(1)Unilocular (common or yellow) adipose tissue
single droplet in fat cell
Distribution:
in subcutaneous tissue throughout the body, mesenterium

64. Function: Storage and mobilization of lipids
The lipids stored in adipose cells are chiefly triglycerides

65. (2). Multilocular adipose tissue (brown fat)
♣ fat cells contain many small lipid droplets,
♣ centrally-located nucleus
♣ rich in mitochondria
♣ rich in capillaries.
Distribution: in certain areas of neonate, greatly reduced in adulthood.
Function: to produce heat

66. Unilocular adipose tissue
Multilocular fat cell
Unilocular adipose tissue
Multilocular adipose tissue
Sympathetic nerve ending

67. Distribution of multilocular adipose tissue
█: mixture of multilocular and unilocular adipose tissue

68. Summary A. Classification of CT B. Loose connective tissue
C. 7 types of cell in CT
1. fibroblast, collagenous fiber synthesis
2. macrophage
3. plasma
4. mast cell
5. fat cell
6. undifferentiated mesenchymal cells
7. leukocyte
D.3 fibers
E.Ground substance
F.Tissue fluid

69. Questions
1. Describe the characteristic ,classification and function of connective tissue?
2. What kind of cells present in connective tissue? And what are the functions of those cells?
3. What is (are) the structure cell(s) of connective tissue?