Cartilage Histology Flashcards
What are the characteristics of cartilage?
Semi-rigid comprised of cells and ECM containg collagen and elastic fibers. It is flexible and resilient, avascular, no nerves
What are chondroblasts?
immature cells that secrete cartilage matrix with mitotic capabilities
What are chondrocytes?
mature cartilage cells in lacunae, surround by ECM and maintain ECM
What fibers make up the ECM?
Type II collagen is predominant, with type I and elastin fibers present
What is the ECM mainly composed of?
Hyaluronic acid, chondroitin sulfate, keratin sulfate, aggrecan
Describe hyaline cartilage and where it can be found
Glassy, surrounded by perichondrium, contains type II collagen
located in articular cartilage(NO PERICHONDRIUM), larynx, trachea, ribs
Describe elastic cartilage and where it can be found
(also contains hyaline) same as hyaline
location: external ear, epiglottis, auditory tube
Describe fibrocartilage and where it can be found
Type I collagen, great strength, lacks perichondrium
Located in IV discs, pubic symphysis, TMJ
What are isogenous groups which chondrocytes can be found in?
gel-like substance that is uniform but blobby, in lacunae
What is territorial matrix?
component of all isogenous groups, territorial matrix is immediately outside of the group, darker stained, consisting of type II collagen, high GAGs
What is interterritorial matrix?
component of all isogenous groups, located outside of the territorial matrix, lighter stained, fewer proteoglycans
What is perichondrium and what two layers does it have?
It is dense irregular CT, contains vascular supply, in hyaline and elastic cartilage only, source of new cartilage cells
- fibrous layer
- chondrogenic layer
What is the fibrous layer ?
the outer layer of the perichondrium that produces type I collagen and elastin, transitional zone between cartilage and surrounding general CT
What is the chondrogenic layer?
inner layer of perichondrium that differentiates into chondroblasts which secretes type II collagen
What does elastic cartilage allow for?
recoil/rebound, retaining shap after deformation, surrounded by perichondrium (contains mix of hyalins and elastic fibers)
What are the two types of cartilage growth, chondrogenesis?
appositional and interstitial growth
How does appositional growth work?
forms new cartilage on surface of existing cartilage, chondrogenic cells located in inner layer of perichondrium, produce type 2 collagen
forms chondroblasts which secrets type II collagen and ECM
How does interstitial growth work?
Takes place within a cartilage mass, the condrocytes divide within lacunae creating new isogenous groups, increasing mass of cartilage
Appositional vs. interstitial growth
A: growth of undifferentiated cells of the perichondrium, widen girth
I: new cells added from chondrocytes within isogenous groups, increase overall size, increase length
Why does cartilage have limited repair capacity?
Due to the avascular nature
How does repair cartilage form and what does it help heal?
Forms when perichondrium is involved: intermediate of hyaline and fibrous cartilage, containing type I and II collagen, can stimulate bone growth
Helps heal bone fractures, age dependent
What is the articular capsule?
outer firbous layer made of dense regular CT, strengthens joint
What is the difference between extrinsic and intrinsic ligaments of the articular capsule?
Extrinsic is separate from the capsule
Intrinsic is part of the fibrous capsule
What is common of articular cartilage?
Avascular, hyaline cartilage, reduces friction, nourished by synovial fluid
What is common of the synovial membrane?
contains synovium and reduces friction by fluid, Lines joint except for articular cartilage, vascular, absorbs shock
What are the two types of synoviocytes?
Type A macrophage-like and Type B fibroblast-like synovial cells
What are characteristic of type A macrophage like synovial cells? (4)
Phagocytic
Contain lysosomes
25% of cells lining synovium
Regulate flammatory events
What are characteristic of type B fibroblast-like synovial cells? (3)
Produce synovial fluid
Produce hyaluronate
Lubricates/nourishes articular cartilage
What is unique of articular cartilage and what are its different zones?
its collagen fibers run perpendicular to tissue surface and form archs to respond to movement
Superficial (tangential), intermediate (transitional), deep (radial), and calcified zones
What is characteristic of the superficial zone of articular cartilage? (3)
Chondrocytes are small and flattened
most superficial is devoid of cells
collagen fibers run parallel to surface
What is characteristic of the intermediate zone? (3)
Chondrocytes slightly larger and round
have both alone and isogenous groups
Collagen has oblique course in matrix
What is characteristic of the deep zone? (3)
Large condrocytes in radial columns
Stacked perpendicular to surface
fibers follow orientation of chondrocyte columns
What is characteristic of the calcified zone? (2)
Rests on cortex of bone
stains darker than the other matrix layers
What occurs in early and late stage of osteoarthritis?
Early: superficial layer of articular cartilage is disrupted
Late: destruction of the cartilage extends to bone where the exposed subchondral bone becomes a new articular surface
Common in weight bearing joints and hands
