Connective tissue

Jun Zhou ( 周俊 )School of Medicine, Zhejiang University

20140408

General features small number of cells and large amount of

extracellular ground substance no polarity vascularized originate from mesenchyme （间充质） -embryonic

CT Function: connection, supporting, protecting,

nutrition, defence and repairing

Mesenchyme （ 间 充质）

---mesenchymal cell: Structure: stellate in shaped with processes a large nucleus,with clear nucleolus slight basophilic cytoplasm

Function: undifferentiated cell multiple developmental potential

→CT cell, SM and endothelial cell

---matrix

Classification ---CT in narrow sense means connetive

tissue proper （ 固 有 结 缔 组 织 ） which include loose CT, dense CT, adipose T and reticular tissue

---CT in wide sense includes cartilage( 软骨 ),

bone and blood

cartilage bone

blood

Features: more types of cells, less fibers Functions: connection, supporting, defence and

repairing consists of cells, fiber and ground substance

Loose connective tissue （疏松结缔组织） (areolar tissue)

Fibers

1. Collagenous fibers （胶原纤维）

2. Elastic fibers （弹性纤维）

3. Reticular fibers （网状纤维）

LM: 1-20 um in diameter Belt-liked wave and branch to form a network Eosinophilic

Collagenous fiber （胶原纤维） (white fiber)

EM: parallel-arranged fibrilsFibril （原纤维） : 20-200nm in diameterHave periodic cross striation at 64-70nm

interval

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 ( 微原纤维 )10-12 nm, electron dense ↑ fibrillin( 原纤维蛋白 )

Elastic fiber （弹性纤维）(yellow 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 striationDistribution: reticular tissue connecting portion, e.g.reticular lamina

Reticular fiber （网状纤维）

Ground substance （基质）---amorphous colloidal substance

---consists of proteoglycan （蛋白多糖） , glycoprotein（糖蛋白） and tissue fluid

①Proteoglycan （ 蛋 白 多 糖 ） -large molecular complex

---glycosaminoglycans （糖胺多糖）chondroitin sulfate （硫酸软骨素）keratin sulfate （硫酸角质素）heparan sulfate （硫酸乙酰肝素）hyaluronic acid （ 透 明 质 酸 ） :

2.5um long--protein

*molecular sieve ( 分子筛 )

② Glycoprotein （糖蛋白） : proteins---fibronectin ( 纤维粘连蛋白 )---laminin ( 层粘连蛋白 )---chondronectin ( 软骨粘连蛋白 )

---Function: Connection affect the differentiation and movement of

cells

③ tissue fluid （组织液） tissue artery → Tissue fluid → vein (lymphatic vessel)

cellsDehydration （脱水）Edema （水肿）

Molecular sieve ( 分子筛 )

Function:

1.Provides mechanical and structural support for metabolism

2.Influences extracellular communication

3.Limitation of inflammation

Cells

ResidentFibroblasts (Fibrocytes) （成纤维细胞） Macrophages (Histiocytes) （巨噬细胞）Plasma cells （浆细胞）Mast cells （肥大细胞） Adipocytes （脂肪细胞）Stem Cells （干细胞） (committed but not differentiated)

TransientNucleated Blood Cells (Lymphocytes,

Plasma Cells, Eosinophils- others occasionally)

---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

Fibroblast（成纤维细胞）

EM: rich in RER, Golgi apparatus and free ribosome

Function: synthesize fibers and ground substance

Three steps:

a.synthesis of procollagen (RER) → process(Golgi) → out of cell

b.procollagen→ tropocollagen → fibril

c.fibril → collagenous fiber

Synthesis of collagenous fiber

( 前胶原蛋白 )

( 原胶原蛋白 )

( 胶原原纤维 )

Fibrocyte ( 纤维细胞 ):

inactive fibroblast

---Structure: spindle-shaped, smallN:small,dark stained Acidophilic cytoplasmaEM: less organelles

---Function:: become into fibroblast for repairing

From monocytes---Structure:LM: round or ovoid-irregular in shape ， short blunt

processes pseudopodium( 伪足 )Small and dark nucleusAcidophilic cytoplasm

Macrophage ( 巨噬细胞 )

EM: rich in Lysosome (primary, secondary) Phagosome( 吞噬体 )← phagocytosis and pinosome ( 吞饮小泡 )←pinocytosis Remnant Microfilament and microtubule Mitochondria

---Function: Chemotaxis: chemotactic factor Phagocytosis:1) Special phagocytosis: recognize bacterium, virus and

foreign cell2) non special: carbon particles, dust and dead cells Secretion: lysozyme, complement and interleukin-I

(IL-1)and interferon(IFN) Antigen presenting function

Mature B lymphocyte---structure: LM: round or ovoidRound eccentrically-located nucleus with more spot-

liked heterochromatinBasophilic cytoplasm

Plasma cell （ 浆 细胞）

EM: RER, free ribosome and Golgi complex

Function: synthesize and secrete immunoglobulin,

Ig-antibody

---structure:

LM: round and large cellSmall dark-stained nucleusBasophilic secreting granules

Metachromatic 异染性

Mast cell （ 肥 大 细胞）

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: involved in allergic reaction

Fat 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

Mesenchymal cell similar to fibrocyte multidifferentiating potential

Leukocytes: neutrophil, acidophil and

lymphocyte

Dense connective tissue

（致密结缔组织）---more fiber

---connection and supporting

1) Regular DCT: parallelly-arranged collagenous fibers special fibroblast

wing-liked processes

---Distribution: tendons, ligament, cornea

2) Irregular DCT: Fiber arranged in bundles, running in different

direction Fibroblast less ground substance

---Distribution: dermis, sclera,capsule of some organs

Adipose tissue （脂肪组织）---LCT+fat cells---White fat T: single fat cellDistribution: subcutaneous tissue, mesenterium---Brown fat T: fat cell contain many small lipid droplets, rich in large mitochondriacentrally-located nucleus rich in cap.Distribution: newborn baby

Reticular tissue （网状组织）---Reticular cells + Reticular fiber + Stroma ---Reticular cells: Irregular 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!