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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 !