Cartilage

Definition of cartilage

• It is a form of connective tissue

composed of cells called chondrocytes

and a highly specialized extracellular matrix

Types of cartilage• According to the number of cells & the nature of the matrix, cartilage are three types

1. Hyaline cartilage 2. Elastic cartilage 3. Fibro-cartilage

Peculiarities of the cartilage:

• avascular• non-nervous • when matrix calcified the chordrocytes die • cartilage cells grow by appositional and

interstitial methods

Perichondium:

• it is a connective tissue membrane which surrounds most cartilage.

• It has• (a) An outer fibrous layer, is composed

mostly of fibroblasts and collagen fibers • (b)A inner cellular or chondrogenic layer, is

composed of chondroblast and chondrogenic cells.

Cartilage which are covered by perichondrium

• All Hyaline cartilage except articular(hyaline) cartilage and epiphyseal cartilage

• Elastic cartilage

Features Hyaline cartilage Elastic cartilageFibrocartilage

Distribution Tracheo-bronchial

cartilage,

costal cartilage of rib and

nasal cartilage, most of

the laryngeal cartilage

Epiglottis,

external ear and ear

canal, auditory tube,

some laryngeal

cartilage( corniculate,

cuneiform etc.)

Intervertebral discs and pubic symphysis, articular discs of temporo-mandibular, sternoclavicular joint, menisci of the knee joint

Features Hyaline cartilage Elastic cartilageFibrocartilage

Function Resistant to

compression, provides

cushioning and low

friction surface for joint

, structural support in

respiratory system

Provides flexible

support

Resist deformation under stress

Hyaline cartilage Elastic cartilage Fibrocartilage

Presence of

perichondrium

Yes (except articular

cartilage and epiphyseal

plates)

Yes No

Undergoes

calcification

Yes ( during

endochondral bone

formation )

No Yes (during bone repair)

Cell types Chondroblasts,

chondrocytes

Chondroblasts,

chondrocytes

Chondrocytes, fibroblasts

Hyaline cartilage Elastic cartilage Fibrocartilage

Extracellular

matrix

Type II collagen fibrils Type II collagen fibrils and

elastic fibers

Type II & type I collagen fibers

Slide

identification

*Cartilaginous matrix: is

homogeneous

*Cells: Lacunae (ovoid space

within the matrix) contain

chondrocyte singly or isogenous

groups

*Perichondrium: surround the

cartilage (if present within the

slide then add this points)

*Cartilage matrix contain

elastic fiber so it is not

homogenous

Lacunae (ovoid space within

the matrix) contain

chondrocyte singly or isogenous

groups

*Perichondrium surround the

cartilage (if present within the

slide then add this points)

Cartilaginous matrix: thick collagen fibres located between parallel rows of condrocytes *Cells: the chondrocytes are smaller than those of hyaline or elastic cartilage and they are arranged in parallel rows between the bundles of thick collagen fibers *Perichondrium: absent

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