Cartilage is a specialized connective tissue that forms parts of the skeletal system and provides structure and flexibility. It consists of chondrocytes embedded in an extracellular matrix containing collagen fibers and ground substance. Cartilage receives nutrients through diffusion as it lacks direct blood vessels. The main types of cartilage are hyaline, elastic, and fibrocartilage, each containing different matrix components and located in specific parts of the body. Bone is a mineralized connectile tissue that makes up the skeletal system and provides structure, support, and protection. It contains osteoblasts, osteocytes, and osteoclasts and has an organic matrix composed of collagen fibers and ground substance that becomes impregnated with calcium phosphate minerals.

2. CARTILAGE
 Specialized /Modified connective tissue
 Forms skeletal basis of some parts of body
 Matrix is firm giving it the characteristic consistency
 Resists compression
 Avascular (nutrients diffuse through matrix)
 Not lymphatics and no nerves, however,
perichondrium is rich in blood vessels

3. PERICHONDRIUM
 Dense irregularly arranged
fibrous tissue
 Ensheaths the cartilage
 Composed of cells &
matrix
 Matrix consists of fibres &
ground substance
 Houses the blood vessels
that nourish chondrocytes
 Present in most of the
hyaline & elastic cartilage
 Absent in fibrocartilage
Fibrous
layer
Cellular
layer

4. CELLS OF THE CARTILAGE
CHONDROBLAST
 Mesenchymal
(embryologically)
 Progenitor of chondrocytes
 Lines border between
perichondrium and matrix
 Produce the intercellular
matrix and collagen fibres
 Cells which become
imprisoned within this
matrix become
chondrocytes.

5. CHONDROCYTE
 Mature cartilage cell
 Reside in a space called
the lacuna
 Isogenous cell group
 Basophilic
 Clear areas = Golgi and
lipid droplets

6. CHONDROCYTE
 Chondrocytes completely
fill their lacunae
 RER and euchromatic
nuclei
 Synthetically active,
secrete matrix
 Synthesize type II
collagen, proteoglycans
and chondronectin.
Cartilage matrix
RER
N

7. MATRIX
 Provides the rigidity, elasticity, &
resilience
 FIBERS
 Collagenous and elastic
 GROUND SUBSTANCE
 Glycosaminoglycans (chondroitin
sulfates & keratan sulfate, hyaluronic
acid)
 Proteoglycans = GAGs + core protein
 Water
 Basophilic
 Territorial matrix (part near the
chondrocytes)- poor in collagen
but rich in proteoglycans, hence
stains more deeply
 Interterritorial matrix

8. CARTILAGE GROWTH
 Interstitial
 Newly formed cartilage
grows by multiplication or
division of pre-existing cells
throughout its substance. E.g
new cartilage formation,
articular cartilage and
epiphyseal end plates of long
bones
 Appositional
 Addition of new cartilage
over the surface
(perichondrium) of existing
cartilage.

9. TYPES OF CARTILAGE
 HYALINE
 ELASTIC
 FIBROUS

10. CARTILAGE: LOCATIONS

11. HYALINE CARTILAGE
 Most abundant cartilage
 Serves as temporary skeleton in
fetus until replaced by bone
 Perichondrium ; a layer of irregular
CT surrounding the cartilage
 Sites: Tracheal rings, nasal septum, larynx,
costal cartilage & articular surfaces of joints
 Cartilage cells: Present singly or in
groups of 2 or 4 cells inside lacunae
 Cartilage Matrix: Collagen type II
 Ground substance: Homogenous,
clearly basophilic containing proteoglycan
aggregates and chondronectin
 Functions: supportive

13. ELASTIC CARTILAGE
 Possesses perichondrium and
identical to hyaline cartilage
except for elastic fibres, hence its
yellow colour
 Sites: Auricle, ext. auditory
meatus, auditory tube, epiglottis,
apices of arytenoid cartilage
 Cartilage cells: larger, more
numerous, packed more closely
 Cartilage Matrix: elastic fibres,
collagen type II
 Ground substance: Rich in elastic
fibres
 Functions: supportive with resilience.
It does not calcify in aging
 Elastic fibers stain with orcein.

14. FIBROCARTILAGE
 Lacks perichondrium
 Sites: intervertebral discs,
arytenoid cartilage (except
apices), pubic symphysis,
manubriosternal joint,
articular disc of TM joint.
 Cartilage cells: fewer,
smaller, scattered singly or in
rows
 Cartilage Matrix: collagen type
I & II
 Ground substance:
acidophilic
 Functions: supportive with
tensile strength
Intervertebral disc

16. Clinical application
 arthritis
 Osteoarthritis

17. bonE
 Specialized/Modified connective tissue
 Highly vascular mineralized connective tissue
consisting of cells and dense intercellular organic
matrix impregnated with inorganic salts.
 Provide support & protection to the vital organs
 Forms skeletal framework

18. Articular cartilage
Spongy bone
Marrow cavity
Compact bone
(location of
haversian systems)
Periosteum
endosteum

19. Bone components
 Cells:
a.Osteogenic or osteoprogenitor cells – form osteoblasts
and osteocytes
b.Osteoblasts- bone-forming cells, which produce organic
components of matrix(the collagen type I and ground
substance
c. Osteocytes- mature bone cells
d.Osteoclasts- bone-removing cells
• Fibers: collagen type I
• Ground Substance: Proteoglycans & glycoproteins

20. • Osteoblast activities are influenced by Parathyroid hormone. It lays
down uncalcified osteoid on top the older bone matrix
• Calcium salts are deposited in the newly formed matrix by process of
calcification.
CALCIFICATION OF THE MATRIX
• Also known as mineralisation
• Osteoblasts secrete a polypeptide called osteocalcin which with other
glycoproteins bind and proliferate Ca2+
• Osteoblasts also matrix vesicles that rich in alkaline phosphatase
which proliferate PO4
- ions concentration
• Both ions form hydroxyapatite [Ca10(PO4)6(OH)2] crystals. This is
the first step
• Accretion of these crystals eventually forms a confluent mass of
calcified material embedding the collagen fibres and proteoglycans

21. The matrix
of bone is a
mixture of
organic
(collagen)
and
inorganic
(calcium
phosphate)
90% of bone is
matrix, with
the remaining
10% made of
osteocytes.

22. Microscopic Anatomy of Bone
Figure 5.3

23. Lamellar arrangement
Slide
 Lamellae
 Rings around the
central canal
 Sites of lacunae
 Lacunae
 Cavities containing
bone cells
(osteocytes)
 Arranged in
concentric rings
Figure 5.3

24. Slide
 Canaliculi
 Tiny canals
 Radiate from the central
canal to lacunae
 Cytoplasmic processes
of osteocytes occupy the
canaliculi
 Form a transport system
Figure 5.3
Lamellar arrangement

25. compact bone
 The morphofunctional unit
of the bone is osteon, or
Haversian system.
 It constitutes one Haversian
canal and the lamellae
around it.
 Lamellar pattern of compact
bone:
i. Haversian system
ii.Interstitial lamellae; formed
by interstitial growth
iii.Circumferential lamellae
formed by appositional
growth

27. T.S. through compact bone
‘Haversian
Systems’

28. Dark spots are called ‘lacunae’ and
would contain osteocytes in living bone
Central canal
containing an
artery, vein,
lymph vessel
and nerves

29. Clinical application
Scurvy
Paget’s disease by persisting woven
bone in adults
Rickets
Osteomalacia
Osteoporosis
Osteogenesis imperfecta