Histology Cartilage (Lect) Flashcards
Where can hyaline cartilage be found?
- Fetal Skeleton
- Articular surfaces of bones
- ventral ends of ribs
- some cartilages of larynx
- tracheal and bronchial rings
- nose
What type of collagen is found in all cartilages?
type II collagen
T or F: the hyaline matrix is rigid, tough, and resistant to tearing?
T
What direction do the collagen fibrils run in hyaline cartilage?
all directions
Can you see the collagen in hyaline cartilage?
No, because they are small and have the same refractive index as the ground substance
What makes hyaline cartilage?
Chondrocytes
What is the consistency of the ground substance in hyaline cartilage?
firm, could be cut with a knife
What is the ground substance made of in hyaline cartilage>
hylauronic acid
proteoglycans (containing keratan sulfate)
Chrodriotin sulfate glycosaminoglycans
multiadhesive glycoproteins (Chondronectin)
What color do the territorial/capsular and interterritorial matrices appear on slides?
Territorial - dark purple
Interterritorial - light purple
What type of protein chains are found in type II collagen?
3 alpha chains
What limits the size of type II collagen in hyaline cartilage?
type IX collagen binding to their surface
What happens to the most superficial layer of type II collagen fibrils in hyaline tissue?
they align in the direction of the stress
What is the orientation of the deep layer collagen fibrils in hyaline cartilage?
Perpendicular to the underlying bone layer
What is the relative size of type II collagen fibrils to type I?
type II is much smaller
Why can the immune system not see antigens on chondrocytes?
the dense matrix molecules block large molecules like antibodies
What is the implication of the immune system not being able to see the antigens on chondrocytes?
For grafts the donors do not have to be matched
How are proteoglycan monomers linked to the hyaluronic acid tubes?
By linker proteins which bind the two together through a non-covalent link
What does GAG stand for?
glycoaminoglycans
Where are GAGs found?
The spindles sticking off the proteoglycan monomers that are bound to hyaluronic acid
What charge to GAG chains have?
negative
What binds to the GAG chains?
water and counterions
What happens to GAGs in compression of hyaline cartilage?
water and counterions are forces out of the tisses and release of the force lets these things back in, tissue springs back into place as a result of repulsion of negative charges
What limits expansion of hyaline cartilage?
collagen fibrils
What are GAGs composed of?
repeating disaccharid units
What happens when proteoglycans are degraded by enzymes?
there is a loss of cartilage and joint function
What are examples of synovial joint molecules that are highly hydrated to act as lubricants?
hyalurnan, lubricin, aggrecan
What lubricant is the primary joint lubricant made by chondrocytes and synovial cells?
lubricin
What type of cartilage will be found in an area where tissue is subject to compression and tension?
fibrocartilage
What are some examples of fibrocartilage in the body?
meniscal cartilages
intervertebral disks
symphysis pubis
ligamentum teres of femur
Characterize the structure/arrangment of condrocytes fibrocartilage
small linear groups, little isogenous clusters or single cell in lacunae
What is the makeup of the matrix in fibrocartilage?
mostly collagen type I
type II and ground substance are in tiny amounts
no real perichondrium
What is fibrocartilage commonly mistaken for?
dense connective tissue
What is the major visual difference between dense connective tissue and fibrocartilage?
the presence of lacunae
How do you tell the difference between fibrocartilage and the nucleus pulposa?
the nucleus doesn’t stain as deep
What kind of cartilage allows for a rigid structure that is also extremely flexible?
Elastic cartilage
Where can elastic cartilage be found?
epiglottis
external ear
auditory tube
certain parts of larynx
What do elastic and hyaline cartilages have in common?
they both contain chondrocytes and lots of type II
T or F: its extremely difficult to tell elastic tissue from collagen unless a special stain is used?
True
What is the coloring of elastic tissue typically?
purple, reddish brown or pink
What is perichondrium?
dense irregular CT with gradual transition into cartilage
T or F: perichondrium contains blood vessels that nourish the cartilage.
T
T or F: perichondrium contains stem cells that can give rise to new cartilage if stimulated by an injury
T
T or F: articular cartilage is full of perichondrium to regerate if degraded?
False, mainly seen in elastic tissue
What acts as lubricant in the synovial cavity of a joint such as the knee?
Hydrouronic acid and lubrican
What nourishes articular (hyaline) cartilage in the joint capsule?
oxygen and nutrients supplied by the synovial fluid
Between cartilage and bone, what stains darker?
bone
What is the capacity for repair in hyaline cartilage?
avascular
aneural
little reparative capacity
What is the capacity for repair in fibrocartilage?
poor vascularity
some innervatino
some reparative capacity
What is the capacity for repair in elastic cartilage?
avascular
aneural
perichondrial repair
What two things do you need one or the other of to get repair in cartilage?
vascularity, or perichondrial stem cells
What kind of cartilage is on the outside of the meniscus?
fibrocartilage
What kind of cartilage is on the inside of the meniscus?
articular cartilage
What causes osteoarthritis in the knee?
wearing away of the articular cartilage eventually causes bone on bone contact
What are 4 major enzymes responsible for joint degradation?
Metalloproteinases
aggrecanases
serine proteinases
cysteine proteases
at what pH are the joint degradation enzymes active?
neutral
What types of cells produce collagenases?
chondrocytes
macrophages
neutrophils
synovial tissues
What is the rate limiting step in degradation by collagenases?
Cutting 3/4 of the way from the amino-terminus of the collagen monomer (at MMP-1, MMP-8, MMP-13)
What are the major risk factors for osteoarthritis?
obesity age previous joint trauma female genetics physical activity surgery to the joint estrogen deficiency
What is the intial skeleton in an embryo formed by?
hyaline cartilage
What type of bone is formed by cartilage being replaced by bone tissue that forms within the cartilage?
endochondral bone
What is the only place in the body that doesn’t have bone thats formed by endochondral growth?
bones in the head
What factors allow cartilage to grow at a faster rate than bone?
It can grow appositionally (inside out) and interstitially (growth on edges, bone can do this too)
What is the difference in the primary and secondary centers of ossificatino?
secondary centers don’t form a bony collar, they only form spongy bone
At what point in development are secondary centers of ossification established?
around birth
What is the growth in long bones after birth dependent on?
interstitial growth of cartilage in the epiphyseal plat
When does the epiphyseal plate close?
at puberty
What does the epiphyseal plate become after/during puberty?
the epiphyseal line
What drives cartilage growth and death at the growth plate?
sex hormones = closure
growth hormone = more growth
What mechanism does cartilage use to grow?
anaerobic glycolysis because many times its in a low oxygen environment
What kind of cells differentiate in to chondroblasts?
mesenchyme
How do condroblasts become chondrocytes?
they secrete ECM separating cells into a lacunae then divide (divison = the landmark)
What type of collagen is found at the growth plate?
type X
What are elastic fibers made of?
fibrillin and elastin
