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CARTILAGE

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General

considerations specialized connective tissue

cells: Chondrocytes matrix: stiff but resilient, fibers are

mostly Collagen; ground substancecontains hyaluronic acid, proteoglycans, &glycoproteins

avascular (cells have low metabolicactivity); nerveless; no lymphatics.

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General

considerations All cartilage is derived from Mesoderm

Perichondrium- dense irregularconnective tissue capsule, source ofnutrients & oxygen for avascularcartilage, enveloping hyaline & elastic

cartilage, except articular cartilage whichcovers the surface of bones & movable joints & which obtains nutrients & oxygenfrom synovial fluid

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chondrocytes peripheral cells are elliptical, long axis

parallel to the surface; inner cells areround, 10-20m in diameter; occuringsingly or in isogenousgroups of up to 8cells

housed in lacunae, perfect fit in vivo synthesize type II collagen, proteoglycans,

& chondronectin

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Chondrocytes:

histogenesis mesenchymal cells retract their extensions,

become rounded chondroblasts chondroblasts multiply rapidly, and form

condensed groups, protochondral tissue from the center outward, chondroblasts

differentiate into chondrocytes, which

secrete matrix around themselves,separating them from one another.peripheral chondroblasts remain in the

perichondrium

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Cartilage growth interstitial growth- from the center

outward, mitosis of chondroblasts thatdifferentiate into chondrocytes appositional growth- from the periphery

inward, perichondrial chondroblasts divide

& differentiate into chondrocytes

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Classification of

cartilage hyaline prototype; most common form;

pliable, distensible; type II collagen isthe predominant fiber

elastic plus many elastic fibers;

characterized by great pliability fibrocartilage matrix contains a

dense network of collagen type I fibers

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Hyaline cartilage Locations:

articular cartilage; costal cartilage Tracheal; Laryngeal; Bronchial walls epiphyseal plate; nasal septum fetal skeleton

cells: Chondrocytes in lacunae extracellular fibers: mostly collagen

matrix: chondronectin, chondroitin sulfate,hyaluronic acid

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Hyaline cartilage

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Hyaline cartilage

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Elastic cartilage essentially identical to hyaline cartilage,

except that, in addition to collagen type IIfibers, it contains an abundant network offine elastic fibers; w/ perichondrium

cells: Chondrocytes in lacunae

extracellular fibers: mostly collagenfibers, with a lot of elastic fibers matrix: chondroitin sulfate,

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Elastic cartilage locations:

epiglottis pinna / auricle ofear

Eustachian tube;

auditory canals laryngeal

cartilages

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Elastic cartilage

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Elastic cartilage

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Fibrocartilage characteristics are intermediate between

those of dense fibrous connective

tissue & hyaline cartilage cells: chondrocytes in lacunae, occuring

singly or in isogenous clusters; oftenarranged in columns

extracellular fibers: Collagen type I matrix: eosinophilic dense fibrous

connective tissue

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fibrocartilage locations:

intervertebraldisks symphysis pubis attachment of

some ligamentsto bones

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fibrocartilage

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Cartilage growth

Appositional - due to differentiation ofperichondrial chondroblasts intochondrocytes, which then secrete collagen &ground substance

Interstitial due to mitotic division ofchondrocytes, forming isogenous groups, &subsequent deposition of collagen & groundsubstance, increasing the intercellulardistance

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Abnormalities

growth:

scurvy- scorbutic rosary inflammation:costochondritis

degenerative:

collagen disorders tumors:

chondroma; chondrosarcoma

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Thank you !