Connective Tissue Li-zhongjie. 1. Introduction Connective tissue is versatile , the types...
-
Upload
felix-casey -
Category
Documents
-
view
219 -
download
2
Transcript of Connective Tissue Li-zhongjie. 1. Introduction Connective tissue is versatile , the types...
Connective Tissue
Li-zhongjie
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 ce
lls embedded in a tissue-specific extracellular ma
trix ( ECM ) .
M esenchymal 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
1.1 Classification Connective Tissue proper Loose connective tissue ※ Dense connective tissue Adipose tissue Reticular tissue Cartilage ※ Bone ※ Blood ※
1.2 Component
Connective tissue
Cell
Extracellular matrix ( ECM ) Fiber
amorphous Ground substance
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, d
efence and repairing
2. Connective tissue proper
Loose(areolar) connective tissue※
Dense connective tissue
Adipose tissue
Reticular tissue
CT in narrow sense means connective tissue proper, include:
loose CT adipose tissue reticular tissue dense CT
2.1 Loose connective tissue
1) consists of 7 types of cells, 3 t
ypes of fiber and ground substanc
e
2 ) The most widely distributed
in the body
3) functions: connection, supporti
ng, defence and repairing
2.1.1 Cells in loose connective tissue
there are 7 types of cells present in LCT ※
Fibroblast※Macrophage※Plasma cell ※ Mast cell ※ Fat cellundifferentiated mesenchymal cell ※ Leukocytes
① fibroblast
---structure:
LM:
•large,flattened cell in shaped
•Large ovoid pale nucleus with clear one-two nucleoli
•Weakly basophilic
EM: rich in RER, Golgi complex a
nd free ribosome
---function: synthesize fibers and ground substance
Synthesis of collagenous fiber in three steps:
a. a. synthesis of procollagen (RER) → process (Golgi) → procollagen → out of cell
b. b. procollagen→ tropocollagen → fibril
c. c. fibril → collagenous fiber
fibrocyte: still state or inactive fibroblast
---structure: spindle-shaped, small small, dark nucleus Acidophilic cytoplasma
EM: less organelles
---function: become into fibroblast for repairing
②macrophage
( The mononuclear phagocyte system )
---structure:
LM: round or ovoid-irregular in shape Small and dark nucleus Acidophilic cytoplasm
EM: rich in lysosome Phagosome: phagocytosis pinosome : pinocytosis Residual bodies 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. Bioactive product secretion: lysozyme,
complement, interleukin-1 (IL-1), interferon
(INF) and growth factor.
d. antigen presenting function
*capture antigen→processes→+ MHC II molecule (major histocompatibility complex molecules) →antigen-MHC II complexes→T lymphocytes
Monocyte in blood is the precursor of macrophages
Liver: Kupffer cells Central nervous system: microglial cell
s Skin: Langhans cells Lymph node: dendritic cells Bone: osteoclast
The mononuclear phagocyte system
③plasma cell---derive from B lymphocyte
---structure:
LM: round or ovoid Round eccentrically-located nucleus with m
ore spot-liked heterochromatin Basophilic cytoplasm
---EM: rich in parallelly arranged RER, free ribosome and Golgi complex
---function: synthesize and secrete antibody( immunoglobulin )
④mast cell
---structure:
LM: round and large cell Small dark-stained nucleus Basophilic secreting granule
s
Basophilic secreting granules:
heparin: an anticoagulant Histamine: increase vascular permeability, capillary
leakage to form edema, promotes the contraction of the smooth muscles
Eosinophil chemotactic factor Other bioactive chemicals
EM Membrane bound granule
s A few Mitochondria A little RER
Function: 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
---structure:similar to fibrocyte
---function: multidifferentiating potential
⑥undifferentiated mesenchymal cell
⑦leukocytes:
Granulocyte: neutrophil, eosinophil and basophil
Agranulocyte: lymphocyte (B, T) monocyte
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
summary
Question
1. What kind of cells present in loose connective tissue? And what are the structure AND functions of those cells?
2.1.2 fibers
Collagenous fiber Elastic fiber Reticular fiber
①collagenous fiber (white fiber)
LM: 1-20 um in diameter Belt-liked wave and branch to form a network Eosinophilic
EM: parallel-arranged fibrilsFibril: 20-200nm in diameter Have periodic cross striation at 64nm interval
collagen (type I and III)
collagenous fibril
collagenous fiber
*formation of collagenous fibers:
② elastic fiber (yellow fiber)
LM: thinner and less, 0.2-1.0 um Slight red (HE) branch and form a networkEM: core: an amorphous substance--elastin-low electron density Peripheral: microfibril 10-12 nm, electron dense Function rubber-like properties
③reticular 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
2.1. 3 ground substance
---amorphous colloidal substance
---consists of proteoglycan, glycoprotein and tissue fluid
Function of the ground substance
Connection affect the differentiation and moveme
nt of cells a barrier to the penetration of foreign
particles
① Proteoglycan: mostly of Proteoglycans and Hyaluronic acid.
Molecular sieve:
•The entangled macro-molecular proteoglycan aggregate forms a bottle brush-like structure
•To exclude or entrap molecules of different sizes
•Serves as a physical barrier to prevent the spread of bacteria and other microorganisms.
② Glycoprotein Fibronectin Laminin chondronectin
③ tissue fluid
Arterial end→ Tissue fluid → venous end →blood steam oxygen, nutrients waste material, carbon dioxide cells
Acts as the midium for exchange of metabolites between circulating and tissue cells
Summary Loose connective Tissue3 fibers and 7 kinds of cells
2.2 Dense connective tissue
---Abundant fibers and few cells
---connection and supporting
Dense regular CT; Dense irregular CT;Elastic CT
2.2.1 regular DCT:
parallelly-arranged collagenous fibers tendon cells: /special fibroblast
/wing-liked processes
---distribution: Tendons Ligament Cornea
2.2.2 irregular DCT: Fiber arranged in bundles,runing in different d
irection Fibroblast less ground substance---distribution: dermis, sclera and capsule of so
me organs
2.2.3 Elastic Tissue: elastic fiber in bundles or in membran
e ligament and large artery
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
2.4 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
The end