Cartilage Histology Flashcards
What are Components of cartilage?
• Like other connect ive t issues
• Extracellular matrix ( fibers &
ground substance)
• Cells are chondroblasts or
chondrocytes
• Avascular
• No nerve supply or lymphatics
Mesenchyme -> Chondro
High O2 becomes bone. Low O2 becomes cartilage.
What are 3 types of cartilage?
- Hyaline
- Elastic
- Fibrocartilage
What is the Perichondrium?
Dense connective tissue interface around
hyaline and elastic cartilage
• Carries the blood supply for avascular
cartilage
• Source of new cartilage cells
What are the Perichondral cell types?
• Fibrogenic cells - outer
perichondrium, become
fibroblasts & give rise to
fibers & ground substance
• Chondrogenic - inner
perichondrium, give rise to
chondroblasts and
osteoprogenitor cells
What are Chondroclasts?
• Associated with cartilage
resorption
• Similar to osteoclasts in
morphology and function
• In endochondral
ossification, their function
is to remove calcified
cartilage
• Appear to enter cartilage
with vasculature (may
derive from monocytes)
Whats in the Matrix?
• Fibers (collagen II) and varying
amounts of GAGs
• Hyaluronic acid (hyaluronan);
chondroitin, keratan & heparin
sulfate
• Amount & type of fiber - pliable
• GAGs (C-4/6-s) control hardness or
rigidity
• Resist compressive forces
• Proteoglycans - core proteins with GAG side chains
• Aggrecan most abundant monomer (h,e)
• Form proteoglycans aggrecates (linked
to long chains of hyaluronic acid by link proteins)
What are the 2 zones?
• Territorial Matrix (TM) matrix
found around each
chondrocyte (high amounts of
GAGs, low collagen)
• Inter-Territorial (IM) found
surrounding territorial matrix;
more collagen II, fewer
proteoglycans
What is Hyaline Cartilage?
- Consistency results from extensive crosslinking
- Long proteoglycan aggregates associate with collagen II fibrils
• Except for articular surfaces, hyaline cartilage is surrounded and nourished by a perichondrium
temporary skeleton in the embryo epiphyseal plates growth stimulated by hormones abnormal growth & calcification influenced by hormones & vitamins
Hormone Effects on Cartilage
• Growth stimulated by: somatotropin,
thyroxine, testosterone
• Matrix formation & growth inhibited by:
cortisone, hydrocortisone, estradiol
Vitamin Effects on Cartilage
Hypovitaminosis A -
retards growth, reduces
width of epiphyseal plate
• Hypovitaminosis C -
inhibits matrix synthesis,
leads to deformation of
epiphyseal plate –>
scurvy
• Vitamin D deficiency -
Chondrocytes proliferate
but matrix does not
calcify properly –> rickets
What is Elastic Cartilage?
- characterized
by increased
flexibility
-flexible,
returns to
original
shape after
deformation
What is Fibrocartilage?
- No perichondrium
-Chondrocytes
in rows
- Abundant collagen I
and collagen I I - Ground substance
has dermatan &
chondroitin sulfate - Much stronger and resistant to
mechanical stress.
— Intervertebral disk
Where is Fibrocartilage located?
- found in attachments
of ligaments to
articular surfaces,
symphysis pubis,
menisci, labrum,
intervertebral discs - may develop as a
result of damage
to hyaline
cartilage
What is Appositional Growth?
• Forms new cartilage on
surface of pre-existing
cartilage
• Occurs within inner layer
of perichondrium
• Chondrogenic cells
produce collagen I (found
in perichondrium)
• After growth initiated,
cells become
chondroblasts and
secrete collagen II &
ground substances
What is Interstitial
Growth?
• Takes place within cartilage mass
itself
• Chondrocytes divide within lacunae,
creating isogenous groups
• New chondrocytes secrete more
matrix, which increases mass of
cartilage
• Overall growth due to secretion of
new matrix
• Limited by avascular nature
