What is the origin of cartilage tissue?
Mesenchyme, which differentiates into chondroblasts
What is the function of chondroblasts?
Secrete extracellular matrix and eventually become chondrocytes (due to becoming entrapped within lacunae)
What is the composition of cartilage?
- no inorganic substances
- mesenchymal cells.
- collagen fibres
- ground substance made up of protein, glycoproteins, glycosaminoglycan’s, water and lipids.
What often surrounds cartilage?
Perichondrium (a form of dense irregular connective tissue)
When does cartilage appear in an embryo?
Around the fifth week
What is an embryo skeleton made of at this time?
Hyaline cartilage (remnants remain as growth plates)
What type of collagen is in hyaline cartilage?
Type 2
Where is hyaline cartilage found?
- Respiratory passageways
- Ends of long bones
- anterior ends of ribs
- foetal skeleton
What is the structure and function of hyaline cartilage?
- firm, flexible and smooth
- allows for movement and support
Is there perichondrium surrounding hyaline cartilage?
Yes, apart from on articulating surfaces
Why does hyaline cartilage rely on diffusion for nutrients?
It is avascular
Where is elastic cartilage found?
- auditory tubes
- external ear
- epiglottis
What is the function of elastic cartilage?
To provide support and maintain shape of structures. Flexibility
Is there perichondrium surrounding elastic cartilage?
Yes
What does the matrix contain for elastic cartilage?
Collagen and many elastic fibres
Is elastic cartilage avascular?
Yes
What type of collagen is fibrocartilage made of?
- 1
- in thick bundles
Where is fibrocartilage found?
Intervertebral discs
Menisci
Pubic symphsis
What is the function of fibrocartilage?
-strongest cartilage so it is used to for support and rigidity. –Found in joints where resistance, durability and strength needed
Is there perichondrium surrounding fibrocartilage?
No
What is the clinical relevance of hyaline cartilage?
- It can calcify in old-age. It is susceptible to degenerative ageing process (increased rate of calcification due to more chondrocytes and cell death).
- Joint pain can be due to erosion of hyaline cartilage at the end of long bones.
What is the rheumatoid arthritis caused by?
- autoimmune disease
- Secondary destruction of articular cartilage
What is the clinical relevance of fibrocartilage?
- Rupture of the annulus fibrosus (intervertebral disc capsule) leads to a slipped disc
- tearing of the menisci
