Cartilage Flashcards
What is cartilage? (2)
- Cartilage is a form of connective tissue composed of chondrocytes and specialized ECM
- Avascular
What is the ECM of cartilage? (3)
o Solid and firm but pliable matrix, making it resilient
o Large amounts of GAGs compared to type II collagen
- allows for diffusion between blood vessels in the surrounding connective tissue and the chondrocytes within the matrix
o Large amount of hydrated proteoglycans make the matrix weak in shear (resists tearing)
Hyaline cartilage:
Location
Function
Presence of perichondrium
Undergoes calcification
Main cell type present
Characteristic features of ECM
Elastic cartilage:
Location
Function
Presence of perichondrium
Undergoes calcification
Main cell type present
Characteristic features of ECM
Fibrocartilage:
Location
Function
Presence of perichondrium
Undergoes calcification
Main cell type present
Characteristic features of ECM
What is the hyaline cartilage matrix defined by? (4)
- Categorized by matrix containing
o Type II collagen fibers
o GAGs
o Proteoglycans
o Multi-adhesive glycoproteins
What are chondrocytes? (2)
o Can be found singularly or in isogenous groups
o In isogenous groups, they indicate that the cells
have recently divided
What are the Regions of the hyaline cartilage matrix? (3)
- Capsular (pericellular) matrix
- Territorial matrix
- Interterritorial matrix
What is the Capsular (pericellular) matrix?
o Ring of more densely staining matrix located
immediately around the chondrocyte
What is the territorial matrix?
o Surrounds the isogenous groups and stains less intensely than capsular matrix
What is the Interterritorial matrix? (2)
o Surrounds territorial matrix
o Occupies the space between groups of chondrocytes
What is the Perichondrium? (3)
o Firmly attached dense irregular connective tissue composed of cells that are indistinguishable from fibroblasts
o Source of new cartilage cells
o When actively growing perichondrium appears in 2 layers
- Inner cellular layer containing chondroblasts
- Outer fibrous layer
What are the features of articular cartilage? (2)
o No perichondrium present
o Exhibits zonation for specific functions
What are the zones of articular cartilage? (4)
- Superficial (tangential) zone
- Intermediate (transitional) zone
- Deep (radial) zone
- Calcified zone
What is the Superficial (tangential) zone? (3)
o Pressure resistant region closest to articular surface
o Chondrocytes are elongated and flattened
o Type II collagen arranged parallel to free surface
What is the Intermediate (transitional) zone? (2)
o Below superficial zone
o Round, randomly distributed chondrocytes
What is the deep (radial) zone?
o Small, round chondrocytes arranged in short columns
perpendicular to free surface
What is the calcified zone? (2)
o Calcified matrix with small chondrocytes
o Tidemark separates deep zone from calcified zone
How is elastic cartilage distinguished? (3)
- Distinguished by the presence of elastin in the cartilage matrix
- All other components are the same as that of hyaline cartilage
- Does not calcify with the ageing process
What is fibrocartilage? (4)
- Combination of hyaline cartilage and dense regular connective tissue
- Chondrocytes dispersed among collage fibers singularly/in rows/in isogenous groups
- No perichondrium present
- Has type I and II collagen fibers
What is Chondrogenesis? (4)
- Mesenchymal chondroprogenitor cells differentiate into chondroblasts
- These chondroblasts secrete cartilage matrix
- When they are completely surrounded by matrix, they are called chondrocytes
- Mesenchymal tissue immediately surrounding chondrogenic nodules give rise to perichondrium
What are the types of cartilage growth? (2)
- Appositional growth
- Interstitial growth
What is appositional growth? (5)
- Forms new cartilage at the surface of an existing cartilage
- Requires perichondrium
- New cartilage cells are derived from the inner portion of the surrounding perichondrium
- Cells resemble fibroblasts in form and function
o They produce type I collagen - When cartilage growth is initiated, these cells differentiate
What is interstitial growth? (2)
- New cartilage is formed within an existing cartilage mass
- New cartilage cells arise from the division of chondrocytes within their lacunae
How is interstitial growth possible? (4)
This is only possible because:
o The chondrocytes retain their ability to divide
o The surrounding matrix is distensible allowing for cell secretory activity
* As new matrix is secreted, a partition is formed between daughter cells and they each occupy their
own lacuna
* The daughter cells mover further apart as more matrix is secreted
Why is cartilage repair limited? (3)
o Avascularity
o Immobility of chondrocytes
o Limited ability of mature chondrocytes to proliferate
When can cartilage repair occur? (2)
- Repair can occur but only if defect involves perichondrium
- Repair mostly involves production of dense connective tissue
What is Osteoarthritis? (2)
- Degenerative, age-related joint disease characterized by
o Chronic joint pain
o Destruction of articular cartilage
