Cartilage

Question 1

Specialized Connective Tissue

Answer 1

• Cartilage & Bone
  1) Highly specialized type of connective tissue that form the skeletal framework
  2) Distinguished from other C.T by the preponderance of solid intercellular material

Question 2

Cartilage

Answer 2

• specialized C.T. in which the extracellular matrix has a firm consistency but lacks the strength of bone
• Functions:
  Locomotion- responsible for ease with whihc joint surfaces glide over one another
  Support- soft tissues, at points of attachment of tendons and ligament to bone
  Development and growth- primary skeletal tissue of fetus and of long bones after birth

Question 3

Cartilage Features

Answer 3

1) Common features: Cells, Matrix (fibers;ground substance); Unique features: avascular, anervous, no lymph capillaries, one cell type, hard matrix

Question 4

Cartilage Matrix

Answer 4

1) Collagen molecules
2) Proteoglycans
3) Noncallagenous proteins
4) Water 70-80%

Question 5

Collagen Molecules

Answer 5

Type 2 collagen: form majority of the fibrils
Type 11: regulates fibril size
Type 9: facilitate fibril interaction with matrix proteoglycan molecules
Type 10: organizes the collagen fibrils into a 3-dimensional hexagonal lattice

Question 6

Proteoglycans

Answer 6

• 3 types of glycosaminoglycans: hyaluronic acid (HA), chondroitin sulfate (CS), Keratan sulfate (KS)

Question 7

Noncollagenous

Answer 7

Multiadhesive glycoporteins: fibronectin, tenascin, anchorin Cll

Question 8

Cartilage Matrix

Answer 8

Two zones:

a) territorial (capsule) matrix: highly basophilic, forms lacunar wall
b) interterritoral matrix: lightly staining, between cells more fibrous content

Question 9

Cells of Cartilage:

Answer 9

a) general arrangement: gradation of cell size- increases near center; decreases in areas farthest from perichondrium
b) types: 1) chondroblast- immature cartilage forming cells, immediately beneath inner layer of perichondrium, spindle shaped
2) chondrocytes: mature chondroblast (surrounded by matrix, they lie in tiny matrix spaces called lacunae) : chondrocyte function depends on a proper hormonal balance

Question 10

Development of Cartilage

Answer 10

Derived from mesenchyme: precartilaginous tissue; condensation of enlarging and proliferating mesenchymal cells

Two regions:

• Central cells: secrete basophilic matrix material surround themselves with matrix
• Peripheral cells: flatten and become fibroblasts

Question 11

Perichondrium

Answer 11

Not present in-

1) Arease where cartilage forms a free surface as in articular surfaces in joints
2) Areas where cartilage makes direct contact with bone as in nasal and costal cartilages and sites of bone formation
3) Fibrocartilage

Question 12

Growth of cartilage:

Answer 12

Appositional growth: formation of new matrix on pre-existing surface
Transcriptional factor Sox9 is required for the expression specific extracellular matrix such as type 2 collagen and the proteoglycan aggrecan; lack of sox 9 expression prevents the chondrogenic layer to differentiate into chondrocytes

Question 13

Types of cartilages

Answer 13

• Hyaline cartilage: entire skeletal framework of fetus; most abundant form in adult; cell to matrix ratio- low

Question 14

Elastic Cartilage

Answer 14

• has numerous elastic fibers
• found in regions requiring a flexible form of support
• locations: external ear, epiglottis
• cell to matrix ratio high

Question 15

Fibrocartilage

Answer 15

• occurs where a tough support or tensile strength is required
• never occurs alone but merges gradually into the neighboring hyaline cartilage or dense C.T
• transitional type between hyaline cartilage and dense fibrous C.T of tendons and ligaments