Download 3. Connective tissue

Chapter 3
Connective tissue
Connective tissue:
1.cells
2. Fibers
3.Ground substance
extracellular matrix
tissue fluid
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
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
2.
Classification
(1) CT in narrow sense means connetive
tissue proper which include:
loose CT
adipose T
reticular tissue
dense CT
(2) CT in wide sense includes :
cartilage
bone
blood
3.
Loose connective tissue
(areolar tissue)
• consists of cells, fiber and ground
substance
features: have more types of cells and
less fibers
functions: connection, supporting,
defence and repairing
1) Cells:
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
EM:
• rich in RER, Golgi appatatus and free ribosome
---function: synthesize fibers and ground substance
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
fibroblast
fibroblast
fibrocyte
fibrocyte
②macrophage
---structure:
•
•
•
•
LM:
Round, ovoid or irregular in shape
have short blunt processes: pseudopodium
Small and dark nucleus
Acidophilic cytoplasm
•
•
•
•
EM: rich in
a. lysosome
b. Phagosome: phagocytosis
c. Remnant
d. Microfilament and microtubule
---function:
a.
Chemotaxis: chemotactic factor
b. phagocytosis:
(1)Special phagocytosis: recognize
bacterium, virus and foreign cell
phagocytosis
(2)non special phagocytosis: carbon
particles, dust and dead cells
c. secretion: lysozyme, complement and
interleukin-I (IL-1) and interferon (INF)
d. antigen presenting function
③plasma cell
---structure:
LM:
• round or ovoid
• Nucleus with more spot-liked heterochromatin
which located eccentrically
• Basophilic cytoplasm
EM: rich in parallelly arranged RER, free
ribosome and Golgi complex
---function: synthesize and secrete
immunoglobulin, Ig-antibody
④mast cell
---structure:
LM:
• round and large cell
• Small dark-stained nucleus
• Basophilic secreting granules
Basophilic secreting granules:
• heparin: an anticoagulant
• Histamine: cause cap. permeability↑, cap.
leakage to form edema and contraction
of SM
• Eosinophil chemotactic factor
Cytoplasm contain:
• slow reaction
substance
---function: to cause
allergic reaction
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
⑥undifferentiated mesenchymal cell
---structure: similar to fibrocyte
---function: multidifferentiating potential
• ⑦leukocytes: neutrophil, acidophil and
lymphocyte, ect.
neutrophil
acidophil
lymphocyte
2) fibers
①collagenous fiber (white fiber)
LM:
• 1-20 um in diameter
• Belt-liked wave and branch to form a network
• Eosinophilic
EM: parallel-arranged fibrils
Fibril:
• 20-200nm in diameter
• Have periodic cross striation at 64nm interval
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
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
3) ground substance
---amorphous colloidal substance
---consists of proteoglycan, glycoprotein
and tissue fluid
4.
Dense connective tissue
---more fiber
---connection and supporting
1) regular DCT:
• parallelly-arranged collagenous fibers
• tendon cells: /special fibroblast
/wing-liked processes
---distribution: tendons, ligament and cornea
2) irregular DCT:
• Fiber arranged in bundles, runing in different
direction
• Fibroblast
• less ground substance
---distribution: dermis, sclera and capsule of
some organs
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
white fat T
brown fat T
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
I. Multichosen question
• 1.Macrophages can participates in
phagocytosis, immunological reactions
and secrete several important substances,
such as
• A.AKP and lysozyme
• B.Heparin and interferon
• C.Complement and histamine
• D.Antibody and heparin
• E.Lysozyme and complement
• 2.The irregularly arranged dense
connective tissue is usually distributed in
• A.tendon
• B.yellow elastic ligament
• C.dermis of skin
• D.epiglottis
• E.epidermis of skin
II.Fill in the blanks:
• 1.The cell types in loose connective tissue
are
________________,_________________
__, ___________________,
__________________,_______________
__,_______________ and
___________________.
• 2.There are 3 main types of connective
tissue fibers:
_______________,_______________ and
_________________.
Thanks!