MS Tissues Flashcards
3 main types of cartilage
hyaline, fibrous, elastic
hyaline cartilage % water?
70 % (of weight)
hyaline cartilage % collagen?
50% of dry weight
hyaline cartilage % proteoglycan?
and % chondrocytes?
35% dry weight
chondrocytes make up ~ 2%-10% of articular cartilage by volume
What content allows hyaline cartilage to be flexible?
proteoglycans
all connective tissues made of what 3 components? (classical description)
cells, extracellular fibers, ground substance (Classically described this way). A contemporary view: hypocellular tissues containing tissue-specific mesenchymal cells within a specialized extracellular matrix
major fibrous component synthesized by connective tissue cells?
collagen (90% dry weight of dense fibrous tissue eg. tendons or ligaments
major function collagen?
provides tensile strength
how many different types of collagen?
28 (tobias)
Describe the structure of collagen
3 coiled polypeptide chains = alpha chains, which twist around each other in a triple helix configuration –> Hallmark of collagen molecule
What is the most abundant type of cartilage?
Type I
Where is type I collagen found?
skin, bone, tendon, ligament
where is type II collagen found?
cartilage, nucleus pulposus and vitreous humor
In addition to collagen, other main fibrous component of connective tissue matrix
elastin
what are proteoglycans?
a protein core to which glycosaminoglycans are attached
Proteoglycans provide….?
resilience and flexibility; hydrophilic
What is hyaluronic acid (hyaluronan)?
A nonpeptide, conjugated, nonsulfated glycosaminoglycan consisting of repeating units of D-glucuronic acid and D-glucosamine
mineral found in bone matrix is an analogue of the naturally occurring mineral called what?
hydroxyapatite- Ca10(PO4)6(OH)2; 20-40 nm diameter
what 3 hormones regulate serum concentrations of mineral ions?
PTH, calcitonin, Vitamin D
Function of PTH?
increases serum Ca levels
Where does PTH act?
kidney, gut, bone
PTH also acts on kidneys to ______ phosphate reabsorption
decrease
Two major classes of GAGs?
1.) Glucosaminoglycans (heparan sulfate and keratan sulfate) contain D-glucosamine & 2.) Galactosaminoglycans (chondroitin sulfate and dermatan sulfate)contain D-galactosamine.
microscopic appearance of collagen?
discrete fibers with banded pattern (look kind of like multiple herringbone necklaces lined up parallel to one another in pic)-This is only the Fibrillar collagens (I, II, III, and others)
structures of the MS system are predominantly of ________ origin (think embryogenesis); what is one exception
mesodermal; exception is nucleus pulposus
nucleus pulposus = ______ origin
neuroectodermal (notochordal) origin
Two major families of proteoglycans?
Large aggregating proteoglycans and small leucine rich proteoglycan family
Aggregating proteoglycans include:
And are also classified as small or large
Aggrecan and versican
Large
Leucine-rich proteoglycans include:
And are also classified as large or small
biglycan, decorin, fibromodulin, and lumican
Small
The 2 most common GAG’s in articular cartilage?
keratan sulfate and chondroitin sulfate
Most abundant GAG in the body?
Chondroitin sulfate
This GAG is distinguished from chondroitin sulfate by the presence of iduronic acid
Dermatan sulfate
Most negatively charged GAG
Heparan sulfate
Keratan sulfate is a GAG that is prevalent in what two tissues?
bone and cartilage
Nonsulfated GAG?
Hyaluronic acid
Elastic fibers (composed mainly of elastin) make of a majority of the ______ ligament
nuchal ligament
Elastogenesis is reactivated during what phase of tissue injury?
reparative
Elastogenesis can be induced by ?
sustained mechanical stress (ie distraction osteogenesis
Elastic fibers can undergo remarkable elastic deformation or strain of approximately ___% of their resting length, with a maximum extension of ____% before loss of strength.
70%, 220%
Elastin has a relatively low modulus of elasticity (____ to ____ kPa) compared with that of type I collagen ( ____kPa)
300 to 600 kPa; 10^6 kPa
What is fibronectin? Why is it an important part of the extracellular matrix?
a large multidomain glycoprotein that is important for cell adhesion (functions as a scaffold for the deposition of other structures (eg. elastin, collagen, etc)
Bone occurs primarily in these 2 forms:
1-cortical, compact, osteonal bone
2-trabecular, cancellous, spongy bone
Describe the cortical, compact, osteonal bone
Longitudinally oriented, over-lapping, cylindrical Haversian units that are made up of a central Volkmann’s canal surrounded by concentrically arranged bone lamellae
Describe the trabecular, cancellous, spongy bone
thin interconnected rods, plates, and struts called trabeculae
components of periosteum
bone-lining cells, osteoprogenitor cells, osteoblasts; also rich in type I collagen, along with a variety of proteoglycans and appreciable quantities of elastin
Collagen in bone is mostly Type __?
Type I with minor amounts of III and V
Collagen fibrils form the basic scaffold upon which mineralization (of bone) occurs; however, nucleation of mineral crystals is not promoted by collagen but requires the presence of what other matrix proteins?
bone sialoprotein, osteocalcin, and ALP
The ability of bone to remodel adaptively in response to mechanical load = aka ______’s Law
Wolff’s Law
What are Volkmann canals?
From the periosteal and endosteal surfaces, vascular channels called Volkmann’s canals enter the bone at right angles and connect with the haversian canals
What are Haversian canals?
A haversian system (osteon) is composed of 4 - 20 lamellae arranged around a vascular channel (haversian canal). Haversian canals generally run longitudinally, but they can bend and form anastomoses with other haversian canals
What type of cell is in Howship’s lacunae?
osteoclasts
Name the 4 zones of hyaline cartilage
tangential zone, transitional zone, radial zone, calcified zone
The calcified zone is separated from the radial zone by a wavy, irregular bluish line (H&E) called the ______?
tidemark
Mineral composition of bone? % citrate? %carbonate?
Living bone is 5 to 10% water and 70 % mineral. Remaining 20-25% is the organic matrix, which is 90% collagen. Bone mineral is primarily hydroxyl appatite (Ca and PO4 and OH) combined with “small amounts” of other minerals, including carbonate, magnesium, acid phosphate, and other trace impurities. Tobias does not give percentage of these other minerals.
Zone I: Tangential zone
highest cell density; gliding zone in which the cells are somewhat flattened with their long axis parallel to the articular surface.
Zone II: Transitional zone
cells are round or ovoid and appear randomly distributed.
Zone III: Radial zone
cells are larger and are arranged with their long axes approximately perpendicular to the surface
Zone IV: Calcified zone
matrix is heavily infiltrated with hydroxyapatite and is firmly attached to the subchondral bone
collagen turn over in the dog
120 years
What is Aggrecan?
the major proteoglycan in articular cartilage; rich in chondroitin sulfate and keratan sulfate side chains
The large core protein of aggrecan has a molecular weight of ~____kDa.
240 kDa
Isolated aggrecan monomers are heterogenous in size and are made up of ~ __% carbohydrate.
90%
Fibrocartilage consists of chondrocytic cells and is rich in Type __ collagen, but contains relatively small quantities of ___________ (relative to other forms of cartilage)
Type I; small quantities of proteoglycans
Refractile lines that distinctly separate haversian systems from the interstitial systems are the “_____________”.
Refractile lines that distinctly separate haversian systems from the interstitial systems are the “cement lines”.
Methods of treating cartilage defects surgically from Thiede/VCOT 2012 review article; FOR SMALL DEFECTS
Debridement, microfracture, radio frequency, and chondrocyte implantation
Methods of treating cartilage defects surgically from Thiede/VCOT 2012 review article; FOR LARGE DEFECTS
Scaffolds and mosaicplasty
Radio frequency energy: used to melt and remove fibrillated tissue & produce a smooth articular surface. Principle?
ionic current density produces molecular friction in the tissue that results in tissue heating.
Microfracture: perforation of subchondral
plate to allow access to the marrow elements and the potential for the formation of a blood clot to form in
the chondral defect. What does the blood clot serve as and/or provide?
provides a scaffold containing growth factors
and cytokines.
Microfracture: Progenitor cells and bone marrow mesenchymal stem cells, entering
an avascular cartilage defect differentiate
into __________-producing cells, and fill
the defect.
fibrocartilage-producing cells
The blood clot usually induces healing by forming what kind of repair tissue?
fibrous or fibrocartilaginous
What is mosaicplasty?
used to treat full thickness defects;involves the removal cylindrical plugs of osteochondral tissue from the articular cartilage of NWB regions. Plugs are inserted into the full-thickness defect
What is multiple cartilaginous exostoses (MCE)?
a benign bone dz of unknown origin w/ multiple, cartilage-capped bony protuberances that arise from the surfaces of any bone formed by endochondral ossification (aka chondroma, osteochondramatosis)
How does MCE manifest in dogs vs. cats?
dogs-young, growing patients; lesions appear and enlarge during endochodral bone formation. Cats-appears after skeletal maturity
T or F? It has been documented that MCE can undergo malignant transformation to chondrosarcoma or OSA.
True
MCE has been associated with what kind of virus in cats?
FLV
MCE may result from focal or complete failure of the perichondrial RING of ????
Lacroix
What is the ring of Lacroix?
the peripheral constraint of the growth plate
Differential diagnoses for MCE?
osteomyelitis, neoplasia, disseminated idiopathic skeletal hyperostosis, hypervitaminosis A, skeletal coccidioidomycosis, and bone cyst
