1. Chapter 3 Connective tissue

2. 1.       General features:
1)   small number of cells and large amount of extracellular ground substance
2)  extracellular is composed of fibers and amorphous ground substance-matrix
3)   all of them originate from mesenchyme-embryonal 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
---CT in narrow sense means connetive proper which include loose CT, dense CT, adipose T and reticular tissue
---CT in wide sense includes cartilage, bone and blood

5. 3. Loose connective tissue(areolar tissue)
features: have more types of cells and less fibers
functions: connection,supporting,defence and repairing
consists of cells, fiber and ground substance

7. cells: seven types of cells are present in LCT

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

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

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

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. ②macrophage ---structure: LM:
round or ovoid-irregular in shape when it have short blunt processes_pseudopodium
Small and dark nucleus
Acidophilic cytoplasm

13. EM: rich in a. lysosome b. Phagosome← phagocytosis and
pinosome ←pinocytosis
c.  Remnant
d.  Microfilament and microtubule

14. ---function:
a.    Chemotaxis: chemotactic factor
b. phagocytosis:
Special phagocytosis: recognize Bacterium, virus and foreign cell
non special: carbon particles, dust and dead cells
*Phagosome(pinosome) + primary lysosome →secondary lysosome →remnants

15. c.  secretion: lysozyme, complement and interleukin-I (IL-1)and interferon(INF)
b.     antigen presenting function:
*capture antigen→processes→+ MHC II molecule (major histocompatibility complex molecules) →antigen-MHC II complexes→TLC

16. ③plasma cell
---structure:
LM:
round or ovoid
Round eccentrically-located nucleus with more spot-liked heterochromatin
Basophilic cytoplasm

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

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

19. Basophilic secreting granules:
heparin:an anticoagulant
Histamine: cause cap. permeability↑, cap. leakage to form oedema and contraction of SM
Eosinophil chemotactic factor
Cytoplasm contain:
leukotriene- slow reaction
substance
---function: cause allergic
reaction

20. 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

21. ⑥undifferentiated mesenchymal cell
---structure:similar to fibrocyto
---function:multidifferentiating potential
⑦leukocytes: neutrophil,acidophil and lymphocyte

22. 2) fibers

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

24. EM: parallel-arranged fibrils
20-200nm in diameter
Have periodic cross striation at 64nm interval
*formation: Extracellular polymerize
collagen(type I and III) →collagenous fibril → collagenous fiber

25. ② 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

26. ③reticular fiber LM: thin and less,0.2-1.0 um in diameter
Branch to form network
Argyrophilic fiber(silver impregnation method)
EM:
type III collagen
64nm cross striation
---distribution:
reticular tissue
connecting portion, e.g.reticular lamina

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

28. ①proteoglycan-large molecular complex
---glycosaminoglycans:
chondroitin sulfate
keratin sulfate
dermatan sulfate
heparin sulfate
hyaluronic acid: 2.5um long
--protein
*molecular sieve

29. ② glycoprotein: proteins
---fibronectin
cells←fibronectin→collagen ↓
proteoglycan
---laminin
---chondronectin
---function:
Connection
affect the differentiation and movement of cells

30. ③ tissue fluid
tissue
artery → Tissue fluid → vein →blood steam
cells
dehydration
oedema

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

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

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

34. 3) elastic T:
elastic fiber in bundles or in membrane
ligament and large artery

35. 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

37. 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