Cartilage Histology Flashcards
What are the cells in cartilage?
chondroblasts
chondrocytes
what are chondroblasts?
cells that secrete cartilage matrix
mitotic capabilities
What are chondrocytes?
mature cartilage cells in lacunae
surrounded by and maintain matrix
What type of collagen is predominant in cartilage matrix?
type II (type I is in fibrocartilage and outer perichondrium in smaller amounts)
What is the ground substance of cartilage made of?
proteoglycans: hyaluronic acid chondroitin sulfate keratin sulfate aggrecan
What are the types of cartilage?
hyaline
elastic
fibrocartilage
What characterizes hyaline cartilage/where is it found?
surrounded by perichondrium (except articular)
type II collagen
location: articular cartilage, larynx, trachea, ribs, embryonic dev.
Where is elastic cartilage found?
external ear, epiglottis
Where is fibrocartilage found?
Location: intervertebral discs, pubic symphysis, TMJ
How are chondrocytes arranged in hyaline cartilage?
in isogenous groups
What is territorial matrix
immediately surrounding and encompassing isogenous grps moderately staining (darker than interterritorial matrix) high GAGs, less collagen
What is interterritorial matrix?
surrounds territorial matrix
light staining
more collagen, fewer proteoglycans
What is perichondrium?
dense irregular CT = outer boundary of cartilage
contains a vascular supply
NOT on fibrous cartilage
source of new cartilage cells
What are the two layers of perichondrium?
Fibrous = outer chondrogenic = inner
What is the fibrous layer of the perichondrium?
outer layer that produces type I collagen and elastin
What is the chondrogenic layer of the perichondrium?
inner layer that differentiates into chondroblasts
secretes type II collagen
What is elastic cartilage?
hyaline cartilage + elastic fibers w/in matrix
surrounded by perichondrium
elastin stains dark purple/black
What characterizes fibrocartilage?
combo of hyaline cartilage and dense regular CT type I and II collagen less cartilage matrix NO perichondrium withstands compression and shearing
What does fibrocartilage look like under microscope?
less matrix
chondrocytes aligned in rows and isogenous grps
fibers oriented in direction of functional stress
What is appositional growth?
growth from perichondrium: produce type I collagen
forms new cart on surface of existing cart
growth initiated –> chondroblasts –> secrete type II collagen and ground substance
What is interstitial growth?
Takes place w/in cartilage mass
chondrocytes divide w/in lacunae –> more isogenous grps
secrete more matrix –> overall size increase
limited by avascular nature
What is repair cartilage?
forms when perichondrium is involved
matrix = in btw of hyaline and fibrous cartilage
types I and II collagen
can stimulate bone growth/ heal bone
How is cartilage repair limited?
cartilage is avascular –> repair capacity limited
age dependent
What are extrinsic ligaments?
separate from joint capsule
What are intrinsic ligaments?
part of fibrous capsule
What characterizes articular cartilage?
hyaline cartilage, but NO perichondrium
reduces joint friction
avascular; no nerve supply
nourished by synovial fluid
What are the types of synoviocytes?
type A macrophage-like
type B fibroblast-like
What characterizes type A macrophage-like synovial cells?
phagocytic
contain lysosomes = clear debris
25% of cells lining synovium
regulate inflammation
What characterizes type B fibroblast-like synovial cells?
produce synovial fluid = plasma filtrate
produce hyaluronate
lubricates/nourishes articular cartilage
What does hyaluronate do?
combines w/ synovial fluid via H2O
What are the zones of articular cartilage?
superficial
intermediate
deep
calcified
What characterizes the superficial zone of articular cartilage?
chondrocytes small and flattened parallel to surface
most superficial region = no cells
collagen fibers fun parallel to surface
What characterizes the intermediate zone of articular cartilage?
chondrocytes slightly larger and round; alone and in iso grps
collagen in oblique course
What characterizes the deep zone of articular cartilage?
large chondrocytes in radial columns
stacks perpendicular to articulating surface
collagen follow orientation of chondrocyte columns
What characterizes the calcified zone of articular cartilage?
rests on bone underneath
matrix of this layer stains slightly darker than other layers
