Cartilage Tissue

Question 1

Characteristics of Cartilage

Answer 1

1) Semirigid supporting tissue
2) Strong by slightly flexible
3) Withstands compressive forces
4) Avascular, Alymph, Aneural

Question 2

Types of Cartilage

Answer 2

1) Hyaline
2) Elastic
3) Fibrocartilage

Question 3

Hyaline

Answer 3

Location:
- nose
- articular surfaces
- costal cartilage
- respiratory
- fetal
Matrix Composition: 
- Type II Collagen; anchors ground substance
- Chrondroitian Sulfate; binds H2O, resists compression (Shock absorbing)
Cellular Composition:
- chondrocytes
- chondroblasts

Question 4

Chondrocytes

Answer 4

• large, round, mature, throughout matrix, live in lacuna
• individual, or isogenous
• responsible for some growth; most maintenance of cartilage matrix

Question 5

Chrondroblasts

Answer 5

• immature cells, small, ovoid, at periphery

- contribute to growth and repair of cartilage matrix

Question 6

Perichondrium

Answer 6

• transition tissue at periphery of cartilage
• vasculature for growth
  Chondrogenic Perichondrium
• inner layer
• chondroblasts and Type II Collagen
  Fibrous Perichondrium
• outer layer
• fibroblasts and Type I Collagen
  *Perichondrium is absent on articular cartilage

Question 7

Elastic Cartilage

Answer 7

Location:
- external ear
- auditory tube
- epiglottis 
- larynx
Composition:
- type II Collagen
- Chondroitin Sulfate
- Elastic Fibers(provide more elasticity than HC; short sinusoidal lines in matrix)
- Chrondrocytes
- Chondroblasts
- Perichondrium
*Fresh => more yellow

Question 8

Fibrocartilage

Answer 8

Location:
- IVD
- Pubic Symphysis
- Articular Discs
- Menisci of Knee
*Where requires: tough support/tensile strength
Composition
- Type I Collagen (Tougher)
- Type II Collagen
- uniformly fibrous in appearance
- chondrocytes are isogenic
- no true perichondrium
- merges into HC or Dense fibrous tissue

Question 9

Cartilage Growth Mechanism

Answer 9

Interstitial Growth
- endogenous; from within
- depends on mitotic and secretory ability of chondrocytes
Process:
1-chondrocytes divide inside lacuna
2-separate by secreting matrix between
3-well early, slow as cartilage matures (less effective)
4-isogenous group more prevalent later on
Appositional Growth
-exogenous, from outside
- depends on perichondrium function
Process:
1-perichondrial chondroblasts secrete new matrix on existing cartilage; perichon pushes outward
2-as chondroblasts lag; they turn into chondrocytes
*Articular has no perichondrium/no appositional growth
*Appositional and Interstitial can happen at same time

Question 10

Endochondral Ossification

Answer 10

• Hyaline cartilage replacement in the development of long bones

Question 11

Endochondral Ossification Process

Answer 11

Mesenchymal Cells
- exist in fetal areas
- multipotential cells
- some => chondrogenic cells => chondroblasts
Chondroblasts
- produce Hyaline cartilage
- interstitial and appositional growth
- vasculature from surrounding mesenchyme
- peripheral changes: cartilage cells die => bone cells
- vasculature grows through perichondrium mid-diaphysis
- primary ossification center; nutrient artery
- mesenchymal cells => osteogenic cells => osteoblasts; secrete new bone matrix on the old cartilage matrix

Question 12

How Endochondral Ossification Happens

Answer 12

• highly vascular primary ossification center causes the cartilage cells to die; cartilage calcifies
• osteoblasts secrete osteoid onto the calcified cartilage matrix
• osteoid; unmineralized bone matrix
• becomes mineralized with hydroxyapatite
• thickens peripherally into compact bone
• central region is reabsorbed