Dr. Amam Ali Amam PhD: Periodontal Disease

Dr. Amam Ali AmamPhD: Periodontal Disease

Dr. Amam Ali AmamPhD: Periodontal Disease

Cartilage

Cartilage, Definition

Is a special form of connective tissue in

which the firm consistency of the extra-

cellular matrix allows the tissue to bear

mechanical stresses.

Is a semi-rigid form.

Is a special form of connective tissue in

which the firm consistency of the extra-

cellular matrix allows the tissue to bear

mechanical stresses.

Is a semi-rigid form.

Cartilage

Cartilage is characterized by:

an extracellular matrix enriched

with glycosaminoglycans and

proteoglycans, macromolecules

that interact with collagen and

elastic fibers.

Cartilage is characterized by:

an extracellular matrix enriched

with glycosaminoglycans and

proteoglycans, macromolecules

that interact with collagen and

elastic fibers.

Cartilage, Functions

1- Bearing mechanical stresses. 1- Bearing mechanical stresses.

2- Support soft tissue. 2- Support soft tissue.

4- Developmental and growth of long

bones

before and after birth.

4- Developmental and growth of long

bones

before and after birth.

3- Shock-absorbing and sliding area

for joints and facilitates bone

movements.

(Because it is smooth surfaced and

resilient)

3- Shock-absorbing and sliding area

for joints and facilitates bone

movements.

(Because it is smooth surfaced and

resilient)

We have to study :• 1- cells• 2- fibers• 3- ground substance

We have to study :• 1- cells• 2- fibers• 3- ground substance

Cartilage is a connective tissue

2- Ground substance2- Ground substance1- Fibers1- Fibers

1- CellsCalled Chondrocytes

1- CellsCalled Chondrocytes

Cartilage consist of:

2- Extracellular matrix2- Extracellular matrix

1- Collagen.1- Collagen.

2- Elastic .2- Elastic .

1- Hyaluronic acid.1- Hyaluronic acid.

2- Proteoglycans.2- Proteoglycans.

3- Small amount ofseveral glycoproteins

3- Small amount ofseveral glycoproteins

• It is derived from chondroblast, which

resembles fibroblast

• It synthesizes and secretes the

extracellular matrix .

• It is interacted in the matrix that it’s

secretes it!

• Histological: it is seen in cavities called

lacunae.

• It is derived from chondroblast, which

resembles fibroblast

• It synthesizes and secretes the

extracellular matrix .

• It is interacted in the matrix that it’s

secretes it!

• Histological: it is seen in cavities called

lacunae.

Chondrocyte

Variations in the composition of these

matrix components produce three

types of cartilage adapted to local

biomechanical needs .

Variations in the composition of these

matrix components produce three

types of cartilage adapted to local

biomechanical needs .

3 Types of cartilage

1- Hyaline cartilage. 1- Hyaline cartilage.

2- Fibro cartilage.2- Fibro cartilage.

3- Elastic cartilage.3- Elastic cartilage.

Articular cartilage.Articular cartilage.

1- Hyaline cartilage. 1- Hyaline cartilage.

It is the most common type & the best

studied of the three forms. It is the most common type & the best

studied of the three forms.

Small aggregation of chondrocytes

embedded in an amorphous matrix of

ground substance reinforced by collagen

fibers ( II )

Small aggregation of chondrocytes

embedded in an amorphous matrix of

ground substance reinforced by collagen

fibers ( II )

1- Hyaline cartilage, cont... 1- Hyaline cartilage, cont...

Location:

1- in the articular surfaces of the

movable joints.

2- in the walls of larger respiratory

passage

(nose, larynx, trachea, bronchi).

3- the ventral ends of the ribs

Location:

1- in the articular surfaces of the

movable joints.

2- in the walls of larger respiratory

passage

(nose, larynx, trachea, bronchi).

3- the ventral ends of the ribs

40 % of the dry weigh of Hyaline Cartilage consist of : 40 % of the dry weigh of Hyaline Cartilage consist of :

1- collagen embedded in a firm

1- collagen embedded in a firm

2- hydrated gel of Proteoglycans.2- hydrated gel

of Proteoglycans.3- structural

Glycoproteins 3- structural

Glycoproteins

Hyaline cartilage

Hyaline cartilage

Cartilage matrix

Is a tissue intermediate between dense

connective tissue and hyaline cartilage.

Is a combination of dense supporting tissue

and cartilage.

Presents in regions of the body subjected to

pulling forces.

Is characterized by a matrix containing a dense

network of coarse type I collagen fibers.

It contains chondrocytes (singly or groups).

Is a tissue intermediate between dense

connective tissue and hyaline cartilage.

Is a combination of dense supporting tissue

and cartilage.

Presents in regions of the body subjected to

pulling forces.

Is characterized by a matrix containing a dense

network of coarse type I collagen fibers.

It contains chondrocytes (singly or groups).

2- Fibro cartilage.2- Fibro cartilage.

2- Fibro cartilage, cont...2- Fibro cartilage, cont...

It is found at :

- intervertebral discs.

- the symphysis pubica.

- the knee joint.

- the mandibular joint.

- the sternoclavicular Joint.

- the shoulder Joint.

- Ligaments and the connections of some

tendons of bone.

It is found at :

- intervertebral discs.

- the symphysis pubica.

- the knee joint.

- the mandibular joint.

- the sternoclavicular Joint.

- the shoulder Joint.

- Ligaments and the connections of some

tendons of bone.

Fibrocartilage

3- Elastic cartilage.3- Elastic cartilage.

Elastic Cartilage, characterized by its

great pliability, contains significant

amounts of the protein elastin in the

matrix.

The more pliable and distensible elastic

cartilage possesses, in addition to

collagen type II, an abundance of elastic

fibers within its matrix.

Elastic Cartilage, characterized by its

great pliability, contains significant

amounts of the protein elastin in the

matrix.

The more pliable and distensible elastic

cartilage possesses, in addition to

collagen type II, an abundance of elastic

fibers within its matrix.

3- Elastic cartilage, cont...3- Elastic cartilage, cont... Elastic Cartilage is found in:

- The auricle of the ear.

- The walls of the external auditory

canal.

- The auditory (Eustachian) tube.

- The epiglottis.

- The larynx.

Elastic Cartilage possesses a

perichondrium (like hyaline

cartilage) .

Elastic Cartilage is found in:

- The auricle of the ear.

- The walls of the external auditory

canal.

- The auditory (Eustachian) tube.

- The epiglottis.

- The larynx.

Elastic Cartilage possesses a

perichondrium (like hyaline

cartilage) .

Elastic cartilage

Articular cartilageArticular cartilage

Covers the surface of the bones of

movable joints.

Is devoid of perichondrium.

Is sustained by the diffusion of

oxygen and nutrients from the

synovial fluid.

Covers the surface of the bones of

movable joints.

Is devoid of perichondrium.

Is sustained by the diffusion of

oxygen and nutrients from the

synovial fluid.

PerichondriumPerichondrium

At the periphery of mature cartilage is

a zone of condensed supporting tissue

called perichondrium containing

chondroblasts with cartilage – forming

potential .

At the periphery of mature cartilage is

a zone of condensed supporting tissue

called perichondrium containing

chondroblasts with cartilage – forming

potential .

PerichondriumPerichondrium

• Is a sheath of dense connective tissue

that surrounds cartilage in most

places, forming an interface between

the cartilage and the tissue supported

by the cartilage.

Most cartilage is devoid of blood vessels

• Is a sheath of dense connective tissue

that surrounds cartilage in most

places, forming an interface between

the cartilage and the tissue supported

by the cartilage.

Most cartilage is devoid of blood vessels

PerichondriumPerichondrium

• All cartilage is covered by a layer of dense connective tissue (perichondrium)

(except in the articular cartilage of joints & fibro cartilage).

• It’s essential for the growth & maintenance of cartilage.

• It’s rich in collagen type I fibers & contains numerous fibroblasts.

• contains nerves lymphatic vessels.

• All cartilage is covered by a layer of dense connective tissue (perichondrium)

(except in the articular cartilage of joints & fibro cartilage).

• It’s essential for the growth & maintenance of cartilage.

• It’s rich in collagen type I fibers & contains numerous fibroblasts.

• contains nerves lymphatic vessels.

• Nutrition• Growing• Regenerating• Degenerative• Histogenesis

• Nutrition• Growing• Regenerating• Degenerative• Histogenesis

Cartilage Properties

Nutrition: is nourished by the diffusion of nutrients from capillaries in adjacent connective tissue (perichondrium) or by synovial fluid from joint cavities.

• Cartilage has no lymphatic vessels or nerves.

Nutrition: is nourished by the diffusion of nutrients from capillaries in adjacent connective tissue (perichondrium) or by synovial fluid from joint cavities.

• Cartilage has no lymphatic vessels or nerves.

Cartilage Properties

Growth : 1- Interstitial growth

2- Appositional growth Growth : 1- Interstitial growth

2- Appositional growth

• In all 3 forms, Cartilage is avascular (no vascular).

• In all 3 forms, Cartilage is avascular (no vascular).

1- Interstitial growth:

Resulting from the mitotic division of preexisting Chondrocytes.

Less important process.

important in increasing the length of long bones

occurs during the early phase of cartilage formation.

1- Interstitial growth:

Resulting from the mitotic division of preexisting Chondrocytes.

Less important process.

important in increasing the length of long bones

occurs during the early phase of cartilage formation.

The Growth of CartilageThe Growth of Cartilage

2- Appositional growth

Resulting from the differentiation of perichondrial cells.

Grows in girth only by opposition.

2- Appositional growth

Resulting from the differentiation of perichondrial cells.

Grows in girth only by opposition.

HistogenesisHistogenesis

A- mesenchyme.

B- Mitotic Proliferation of mesenchyme.

C- Chondroblasts. D- rise to isogenous

group.

A- mesenchyme.

B- Mitotic Proliferation of mesenchyme.

C- Chondroblasts. D- rise to isogenous

group.

Perichondrium & Hyaline cartilage

Degenerative changesDegenerative changes

• Hyaline cartilage is more susceptible to

degenerative aging processes ( in

contrast of other tissues).

• Calcification of the matrix, preceded by

an increase in the size & volume of the

chondrocytes and followed by their

death.

• Hyaline cartilage is more susceptible to

degenerative aging processes ( in

contrast of other tissues).

• Calcification of the matrix, preceded by

an increase in the size & volume of the

chondrocytes and followed by their

death.

Poor Regeneration of Cartilage TissuePoor Regeneration of Cartilage Tissue

• Except in young children, damage

cartilage regenerates with difficulty &

often incompletely by activity of the

perichondrium, which invades the

injured area and generates new

cartilage

• Except in young children, damage

cartilage regenerates with difficulty &

often incompletely by activity of the

perichondrium, which invades the

injured area and generates new

cartilage

Fibrocartilage, young animal