5.1 lect - bone & cartilage Flashcards
cartilage and bone are derived from the __, which is derived from the __
mesenchyme
mesoderm
3 regions of long bone
epiphysis - head
metaphysis - neck
diaphysis - shaft
macroscopic descriptions of bone
compact
spongy (cancellous)
microscopic descriptions of bone
woven
lamellar
-appositional
-haversian
outer surface of bone
periosteum
inner surface of bone
endosteum
T/F all bone surfaces are lined with cells
true
what are the two layers of periosteum?
outer fibrous
inner cellular
how is bone prepared in a histological section?
demineralized
soft tissues removed
what is the name for circular bone structure
osteon or
haversian system
what are two types of lamellar bone growth?
haversian growth (concentric rings) apositional growth (sheets)
what embryonic tissues does bone come from?
- axial skeleton - sclerotome (somites, paraxial mesoderm)
- appendicular skeleton + sternum - somatic mesoderm (lateral plate mesoderm)
- facial bones, parts of skull, clavicle - neural crest cells (ectomesenchyme)
what embryonic tissue does most of the axial skeleton come from (except sternum, facial and some other bones of skull) ?
sclerotome
somites, paraxial mesoderm
what embryonic tissue does most of the appendicular skeleton and sternum come from (except clavicle) ?
somatic mesoderm
lateral plate mesoderm
what embryonic tissue do the clavicle and facial bones come from ?
neural crest cells
ectomesenchyme
how is intramembranous bone formed?
begins with a fibrous layer and bone is made directly (no cartilage intermediate)
how is endochondral bone formed?
shape made from hyaline cartilage, then turned into bone with osteocytes and vascularization
what are two types of initial bone development?
intramembranous (fibrous layer - bone)
endochondral (hyaline cartilage shape - bone)
what kinds of bones develop by endochondral ossification?
extremeties and weight bearing bones of axial skeleton
what kinds of bones develop by intramembranous ossification?
flat bones of face and skull, mandible, clavicle
mesenchyme
part of embryonic mesoderm that develops into connective tissues and other important tissues
appositional growth
growth on an existing surface. surrounding mesenchyme gives rise to osteoprogenitor cells that come into contact with initially formed bone and differentiate into bone producing cells
what does the axial skeleton include
spine, ribs, skull
is the shoulder girdle part of the axial or appendicular skeleton?
appendicular
is the pelvic girdle part of the axial or appendicular skeleton?
appendicular
bone collar
layer of bone around diaphysis of a cartilage model of developing bone
- located between periosteum and cartilage
- first sign of ossification of long bones
primary ossification center
in diaphysis of long bones, site in hyalin cartilage model where bone begins to form
secondary ossification center
in epiphysis of long bones, formation of bone and breakdown of hyalin cartilage model
in diaphysis of long bones, site in hyalin cartilage model where bone begins to form
primary ossification center
in epiphysis of long bones, formation of bone and breakdown of hyalin cartilage model
secondary ossification center
where are the primary and secondary ossification centers?
in long bones
primary - diaphysis
secondary - epiphysis
woven bone
(also primary, bundle, nonlamellar)
- initially formed and immature
- more cells, random pattern
- major type in fetus
primary bone
(also woven, bundle, nonlamellar)
- initially formed and immature
- more cells, random pattern
- major type in fetus
bundle bone
(also primary, woven, nonlamellar)
- initially formed and immature
- more cells, random pattern
- major type in fetus
nonlamellar bone
(also primary, woven, bundle)
- initially formed and immature
- more cells, random pattern
- major type in fetus
immature bone
(also primary, woven, nonlamellar, bundle)
- initially formed and immature
- more cells, random pattern
- major type in fetus
lamellar bone
(mature bone)
- fewer cells
- organized layers
- haversian or appositional
mature bone
(lamellar bone)
- fewer cells
- organized layers
- haversian or appositional
osteon
lamellar bone in concentric circles
from haversian growth
calcified cartilage matrix
initial scaffold for new bone deposition
-chondrocytes will apoptose, calcified cartilage removed by phagocytosis, new bone laid down by osteoblasts
this structure is the initial scaffold for new bone deposition
calcified cartilage matrix
-chondrocytes will apoptose, calcified cartilage removed by phagocytosis, new bone laid down by osteoblasts
epiphyseal cartilage
growth plate
- cartilage that remains between epiphysis and diaphysis following secondary ossification center development
- allows for continued long bone growth
growth plate
- epiphyseal cartilage that remains between epiphysis and diaphysis following secondary ossification center development
- allows for continued long bone growth
what are the zones of the epiphyseal growth plate?
- rest (reserve cartilage)
- proliferation
- hypertrophy (maturation)
- calcification & degeneration)
- ossification & resorption (of calcified cartilage)
articular cartilage
hyaline cartilage at ends of long bone in synovial / moveable joints
-allows smooth gliding of articulating surfaces
hyaline cartilage at ends of long bone in synovial / moveable joints
articular cartilage
epiphyseal line
what is left of epiphyseal plate when growth is completely finished
-no cartilage remains between epiphysis and diaphysis, all replaced by bone
what are the two kinds of tissue that bone grows within
mesenchyme (intramembranous ossification)
cartilage (endochondral ossification)
how does bone qualify as specialized connective tissue?
cells suspended in an extracellular matrix
are most bones formed by endochondral or intramembranous ossification?
endochondral
limb bones are developed by __ ossification
endochondral
the spine and ribs are developed by __ ossification
endochondral
by what kind of ossification is the shoulder girdle formed?
clavicle - intramembranous
the rest - endochondral
the pelvic girdle is developed by __ ossification
endochondral
where does the hyaline cartilage model for endochondral ossification come from?
mesenchymal cells
when are hyaline cartilage bone models developed?
by week 6 of embryonic development
when does ossification of limb bones begin?
week 8 of embryonic development
when are cartilage models developed and when does ossification of limb bones begin?
cartilage models - week 6
ossification begins - week 8
when in embryonic development do demands on the maternal supply of calcium, proteins, and vitamins increase significantly?
week 8
ossification of cartilage models begins
also intramembranous ossification
in this type of bone formation mesenchyme differentiation, mesenchyme differentiates directly to bone
intramembranous ossification
are flat bones of the skull formed by endochondral or intramembranous ossification?
intramembranous
are facial bones formed by endochondral or intramembranous ossification?
intramembranous
is the clavicle formed by endochondral or intramembranous ossification?
intramembranous
when does intramembranous ossification begin?
week 8
same as endochondral
increases demands on maternal supply of calcium proteins vitamins
what microscopic type of bone is formed via endochondral ossification?
primary or woven
will be replaced by lamellar bone in remodeling
what microscopic type of bone is formed via intramembranous ossification?
primary or woven
will be replaced by lamellar bone in remodeling
what microscopic type of bone is formed via intramembranous vs endochondral ossification?
both form primary or woven bone
will be replaced by lamellar bone in remodeling
steps of intramembranous bone formation
- mesenchymal cells organize into an ossification center with adequate vascularization
- differentiate into osteoblasts
- produce osteoid matrix that will calcify
- trapped cells become osteocytes
- ossification centers grow radially and fuse with others to produce bone
steps of endochondral bone formation
- mesenchymal cells organize into a hyaline cartilage model
- bone collar forms (impedes diffusion of O2 to chondrocytes)
- chondrocytes produce alkaline phosphatase and hypertrophy
- calcification and death of chondrocytes
- blood vessels penetrate bone collar bring osteoprogenitor cells
- osteoblasts add layers of primary bone to calcified cartilage matrix
- calcified cartilage removed by osteoclasts
- appositional bone growth
- secondary ossification center later appears in epiphysis
- primary woven bone replaced by secondary lamellar bone
what is the function of the bone collar?
in endochrondral ossification
impedes O2 diffusion to chondrocytes at primary ossification center, leads to chondrocyte hypertrophy and then death
-then blood vessels penetrate bone collar to bring osteoprogenitor cells
by when is epiphyseal cartilage usually eliminated?
age 20
bony epiphyseal line only
when are the terms intramembranous and endochondral applicable to bone?
during initial laying down (ossification) only
meckel’s cartilage
cartilage structure in mandible that exists for structural support while mandible forms by intramembranous ossification
-regresses and disappears in fetus
cartilage structure in mandible that exists for structural support while mandible forms by intramembranous ossification
-regresses and disappears in fetus
meckel’s cartilage
these cells produce osteoid
osteoblasts
osteoid
new, not yet calcified bone material, recently secreted from osteoblast
osteoblasts secrete
osteoid
and matrix vesicles (aid in calcification)
trabeculae
bone struts during ossification or in spongy bone
how is periosteum formed?
mesenchyme condenses around bone
do vertebrae form via endochondral or intramembranous ossificaiton?
endochondral
when do secondary ossification centers appear?
some before birth
some after birth
where do the osteoblasts come from in endochondral ossificaiton?
some from stem cells in perichondrium
some from stem cells in blood flow
gestational diabetes and retanoic acid exposure through acne and anti-aging creams in the mother can affect embryonic/fetal bone growth how?
can interfere with migration of cranio neural crest cell migration and cause defects in craniofacial bone development
when a cuboidal osteoblast is not actively producing osteoid it will become….
a squamous bone lining cell
T/F osteoclasts are derived from mesenchymal stem cells
false
osteoblasts, bone lining cells, osteocytes are derived from mesenchymal stem cells
-osteoclasts are derived from granulocyte / monocyte progenitor cells
what material is produced by chondrocytes in the zone of hypertrophy?
type I and type X collagen
does the growth plate change thickness during growth?
no
cartilage is resorbed at ~same rate bone is proliferating
in H&E, bone stains __, cartilage stains __
bone eosinophilic
cartilage basophilic
parenchymal means
the native, unique, functionally significant
antonymn of stromal
the antonymn of parenchymal
stromal
the antonymn of stromal
parenchymal
the native, unique, functionally significant
antonymn of stromal
parenchymal
is growth plate usually considered part of the epiphysis or metaphysis?
metaphysis
T/F growth plate is usually considered part of the epiphysis
false
metaphysis
T/F growth plate is usually considered part of the metaphysis
true
