Cartilage

1. CARTILAGE
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2. CARTILAGE
• Cartilage is an avascular, flexible connective tissue located through out the
body ,providing support and cushioning for adjacent tissues.
• Cartilage is composed of cells & extracellular matrix ( ground substance &
fibers)
Chondrocytes
• Cells of cartilage are called Chondrocytes.
• Chondrocytes may occur singly but are frequently clustered.
• Extracellular matrix is secreted by chondrocytes and composed of ground
substance & connective tissue fibers.
• Fibers are of collagen & elastic variety and are embedded in ground
substance.
• Cells occupy smallest spaces called Lacunae (singular lacuna) within the
extracellular matrix .
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3. Perichondrium:
 It is a sheath of dense irrregular connective tissue that covers
cartilage in most(but not all)places.
 Perichondrium contains blood vessels which are responsible for
supply of nutrients and oxygen to the avascular cartilage.
Perichondrium is composed of 2 layers
1. An outer fibrous layer which consist of collagen fibers and
blood vessels,lymphatic vessels and nerves.
2. An inner cellular layer , in which are present fibroblast like
cells called chondrogenic cells, which are capable of
transformation into chondroblasts (cartilage forming cells)
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4.  Cartilage is an avascular.
 Cartilage has no nerve supply or sensory receptors.
 The substances of cartilage is not traversed by any blood vessel or
lymphatic vessel .
 The chondrocytes receive nutrition from blood vessels of
surrounding connective tissue by diffusion through extracellular
matrix.
 In synovial joints, the cartilage also receives nourishment from the
synovial fluid that fills the joint cavities.
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5. Functions of cartilage
Because of its resilient nature, cartilage performs 2
major functions in the adult human body.
1. Functions as shock absorber in various locations
of the body .
2. Covers the articulating surfaces of those bones
which participates in the formation of synovial
joints. (friction-free movement of these joints)
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6. Types of Cartilage
• Three varieties are distinguished on the basis
of types of fibers/fibrils present in the
extracellular matrix.
• HYALINE CARTILAGE
• FIBROCARTILAGE
• ELASTIC CARTILAGE
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7. HYALINE CARTILAGE
• Commonly called ‘’gristle’’
• Upon naked eye examination, the fresh hyaline cartilage gives a bluish –
white translucent appearance resembling that of a frosted glass(hence
the name hyaline i-e glass like)
• When viewed through light microscope has a clear glassy like appearance.
• CELLS OF HYALINE CARTILAGE :
• Cells are chondrocytes, they are large (15-30 m in diameter)
• Rough spherical cells.
• Big centrally placed nucleus showing one or two nucleoli.
• Cytoplasm is granular and basophilic
• Chondrocytes are generally arranged into groups of two to four or more
cells ,which are called isogenic groups.
• All members of isogenic groups occupy a single lacuna
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8. HYALINE CARTILAGE
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9. Distribution of hyaline Cartilage:
Articular cartilages which cover the articulating bone
surfaces in the movable joints.
Cartilage of trachea and bronchi
Nasal cartilage
 forms flexible bridge called costal cartilage , between
the anterior portion of each of the first 10 ribs and the
sternum.
Most of the bones of body first forms as hyaline cartilage
and later become bone in the process called
endochondral ossification.
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11. ELASTIC CARTILAGE
• When fresh appears yellowish and more opaque than
hyaline cartilage.
• Numerous elastic fibers give it a yellow appearance.
• Similar to hyaline cartilage except for presence of
abundant elastic fibers that makes it very flexible
without compromising its strength.
• Found in outer ear , portion of larynx ,auditory canal.
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12. • Chondrocytes are similar in appearnce to those of to hyaline
cartilage .
• They lie within lacunae.
• Occur singly or in isogenic groups of two to four cells.
• Matrix contains large number of elastic fibers which branch and
interlace with each other to form a closely woven network.
• Elastic network is dense in region surrounding the chondrocytes.
• Elastic cartilage is surrounded by perichondrium.
• Unlike hyaline cartilage they don't become calcified with increasing
age.
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16. FIBROCARTILAGE
• Can be regarded as a combination of dense regular connective
tissue and hyaline cartilage .
• Found in body where great strength combined with flexibility and
rigidity is required.
• Chondrocytes have same structure as those of hyaline cartilage but
the arrangement of cells in these two varieties of cartilage is
different from each other.
• Chondrocytes are arranged in parallel rows; each row comprising of
2,4,6 cells.
• Fibrocartilage not surrounded by perichondrium
• Matrix of fibrocartilage stains acidophilic due to abundance of
collagen fibers.
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17. FIBROCARTILAGE
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18. • Like ordinary collagenous connective tissue,
the fibrocartilage develops from fibroblast.
• After producing large quantities of collagen
fibers, some of the fibroblasts differentiate
into chondrocytes and begin to secrete
cartilage matrix containing proteoglycans.
• This amorphous matrix surrounds the
chondrocytes and isolates then from bundles
of collagen fibers.
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19. Distribution of Fibrocartilage
• Found in
• Intervertebral disc
• Disc of pubic symphysis
• Menisci of knee joint
• sternoclavicular joint
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20. SUMMARY OF CARTILAGE
TYPE STRUCTURE FUNCTION
HYALINE CARTILAGE Homogenous matrix with
extremely fine collagenous
fibers provides flexible
support, protects & is
precursor to bone
Articular surface of
bones,nose,wall of
respiratory passages,fetal
skeleton
FIBROCARTILAGE Abundant collagenous
fibers within matrix,
supports, withstands
compression
Symphysis
pubis,intervertebral
disc,knee joint
ELASTIC CARTILAGE Abundant elastic fibers
within matrix, provide
flexibility
Framework of outer ear
,portion of larynx
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21. BONE TISSUE
• Is most rigid of all connective tissues.
• Unlike cartilage, it has a rich vascular supply.
• Bone tissue is composed of several type of bone cells
embeded in a matrix of ground substance, inorganic
salts (calcium & phosphorous) and collagenous
fibers.
• Hardness of bone is due to calcium phosphate
deposited within intracellular matrix.
• Numerous collagenous fibers also embedded within
the matrix, give bone some flexibility.
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22. Spongy & Compact Bone Tissues
Based on porosity ,bone tissue is classified as
• Compact (dense) bone tissue
• Spongy(cancellous) bone tissue
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23. Bone Cells
• Five types of bone cells contained within bone
tissues
1. Osteogenic
2. Osteoblasts
3. Osteocytes
4. Osteoclasts
5. Bone lining cells
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24. Bone Cells
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25. Shapes / Types of bones
• Bones of skeleton are grouped on the basis of
shape into four principle categories
1. Long Bones (femur, tibia, fibula, humerus, radius,
metatarsal & phalanges)
2. Short Bones (Lunate,pisiform,trapezoid)
3. Flat Bones (cranial bones, ribs,bones of shoulder girdle)
4. Irregular bones (vertebrae & certain bones of skull)
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26. Example of Bone types, as classified by
shape
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27. Bones of Skull
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29. STRUCTURE OF TYPICAL BONE
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30. Compact Bone
• The outer covering or the periosteum is made up
of an outer fibrous layer & inner cellular layer,
which contains osteogenic cells.
• Bony tissue is comprised of Haversian systems.
• Each Haversian system consists of centrally
situated Harvesian canal,surrounded by
concentrically arranged lamella.
• Each osteon consists of 5-15 lamellae of bone
matrix that are concentrically arranged around a
longitudinally running central canal called
harvesian canal.
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31. Compact Bone
• Osteocytes in their lacunae are found at regular
intervals betweeen lamellae .
• Neighbouring lacunae are connected with each other
by narrow canaliculi .
• Canaliculi form a network of channels that allow the
flow of nutrients, ions, hormones & waste products
between osteocytes and nearby blood vessels.
• Between osteons there are imcomplete remnants of
osteons,called interstitial systems.
• Perforating (Volkmann’s canal penetrates compact
bone,connecting osteons with blood vessels & nerves
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33. MICROSCOPIC STRUCTURE OF TYPICAL BONE
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34. Spongy Bone
• E.g Sternum,ends of long bones
• Its outermost covering is periosteum
• Haversian systems are absent.
• Bone tissue is made up of trabecule of varying
shapes & sizes joined with each other
enclosing small spaces containing red bone
marrow.
• Inside the trabeculae are osteocytes which lie
within the lacunae
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35. Spongy bone(Cancellous)
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