What is a chondrocyte?
A chondrocyte is a cell that has secreted the matrix of cartilage and has become embedded in it.
What cells are found in cartilage?
Chondrogenic cells –> chondroblasts –> chondrocytes
What is found in the extracellular substance of cartilage?
- Collagen fibers
- Aggregates of proteoglycans rich in chondroitin sulfates.
- Glycoproteins (anchorin, tenascin, fibronectin and chondronectin)
What are chondrogenic cells?
Chondrogenic cells are stem cells for cartilage and can be transformed into chondroblasts.
What are chondroblasts?
Chondroblasts are cells that actively produce the components of extracellular substance during cartilage formation. They will then transform into chondrocytes.
Where and how are the extracellular substances produced and excreted from the chondroblast?
RER –> Golgi –> Constituitive exocytosis
What are the characteristics common for all cartilage types?
- No blood vessels
- Ground substance rich in chondroitin sulphates
- Chondrocytes residing in lacunae: singel or in small groups called isogenous groups.
What are chondral territories?
Chondral territories are small cavities (lacunae) that are surrounded by ground substance.
What is perichondrium?
The perichondrium is a layer of dense connective tissue that covers the cartilage surface.
Where are the blood vessels, supplying oxygen and nutrients present in cartilage?
In the perichondrium of cartilage
What cartilage cells are present in perichondrium?
Perichondrium contains chondrogenic cells which can be activated and become chondroblasts.
How does cartilage grow in size?
- By the growth of apposition: chondrogenic cells present in the perichondrium being activated and becoming chondroblasts producing extracellular substance.
- By interstitial growth: Divisions of chondrocytes in the chondral territories.
Does cartilage have strong regenerative capabilities?
Mature cartilage have very weak regenerative capabilities, especially in elderly persons.
Which cartilage types do have chondral territories?
All cartilage (elastic, fibro and hyaline cartilage) contains chondral territories.
- However, fibrocartilage contains fewer chondral territories.
What collagen type is present in hyaline cartilage between and around the chondral territories?
Collagen type 2
What are the ground substance of hyaline cartilage especially rich in?
The ground substance of hyaline cartilage is especially rich in giant proteoglycan (aggrecan) aggregates.
Where do you find hyaline cartilage?
You find hyaline cartilage in:
- Articular surfaces
- Nose, larynx, trachea, and bronchi
- In the fetus long bones.
What the main property of hyaline cartilage?
Due to highly hydrated proteoglycans (like aggrecan), it is very resistant to compression.
What are GAG chains?
GAG stands for glycosaminoglycan. GAG chains are very polar and attract water. Under pressure of hyaline cartilage, water is pushed out from spaces between GAG chains and negatively charged sulfate residues of FAF chains repel each other.
Which cartilage types contain collagen type 2 and which cartilages contain collagen type 1?
Hyaline cartilage - collagen type 2
Elastic cartilage - collagen type 2
Fibrocartilage - collagen type 1
Where in the body do you find elastic fibers?
Elastic fibers are found in:
- The auricle
- The auditory tubes
- The larynx (e.g. epiglottis)
What is the main property of elastic fibers?
Elastic fibers are very elastic :D
Do all cartilage types contain perichondrium?
No. Elastic and hyaline cartilage contain perichondrium, but fibrocartilage does not.
Where do we find fibrocartilage?
Fibrocartilage is found in:
- The temporomandibular joint
- The intervertebral discs
- The pubic symphysis
- In some attachments to bone (continuous with tendons)
