marieb; fig. 6.1 do you know the four bone classifications? long bone short bone flat bone irregular...

Marieb; Fig. 6.1

Do you know thefour bone

classifications?

Do you know thefour bone

classifications?

long bonelong bone

short boneshort bone

flat boneflat bone

irregular boneirregular bone

Can you identifyeach of these

labeled structures

in a long bone ?


labeled structures

in a long bone ?

Marieb; Fig. 6.3

Marieb; Fig. 6.4


labeled structures

in a flat bone ?


labeled structures

in a flat bone ?

Marieb; Fig. 6.4

In the previous slides, you should have noticed that you labeled compact and spongy bone in both the

long and the flat bone. The flat bone is a ‘sandwich’ of

spongy bone between compact bone. (And you

also did not label an epiphysis or diaphysis in the

flat bone.) The cortex of the diaphysis of the long

bone is primarily made up of compact bone. However, at

its proximal epiphysis, it has a hard outer shell of

compact bone, and is filled with spongy bone.

In the previous slides, you should have noticed that you labeled compact and spongy bone in both the

long and the flat bone. The flat bone is a ‘sandwich’ of

spongy bone between compact bone. (And you

also did not label an epiphysis or diaphysis in the

flat bone.) The cortex of the diaphysis of the long

bone is primarily made up of compact bone. However, at

its proximal epiphysis, it has a hard outer shell of

compact bone, and is filled with spongy bone.We can use these two

architectural differences in bone construction (spongy and compact) to identify

differences in the function of some bones.

We can use these two architectural differences in bone construction (spongy and compact) to identify

differences in the function of some bones.

The density of compact compact bonebone provides

considerable strength and stiffness to our

skeletal system.

You will see the thickness of compact

bone increase down the shafts of long bones such as this femur.

These areas must not only respond to high loads imposed down

the length of the bone during weight bearing, but must also respond

to torsional and bending stresses.

The density of compact compact bonebone provides

considerable strength and stiffness to our

skeletal system.

You will see the thickness of compact

bone increase down the shafts of long bones such as this femur.

These areas must not only respond to high loads imposed down

the length of the bone during weight bearing, but must also respond

to torsional and bending stresses.

CancellousCancellous bone is also often called spongyspongy bone. This is the type of bone

that makes up the interior of most bones

(though definitely not the shaft of long bones as

you have already seen).

Spongy bone is made up of trabeculaetrabeculae. These

trabeculae align themselves in the

direction of the imposed stress on a bone. The

presence of these trabeculae make

cancellous bone appear more porous. This makes it lighter in weight than compact bone, but still provides considerable

strength. However, it is not as strong as compact bone, so is more easily

fractured.

CancellousCancellous bone is also often called spongyspongy bone. This is the type of bone

that makes up the interior of most bones

(though definitely not the shaft of long bones as

you have already seen).

Spongy bone is made up of trabeculaetrabeculae. These

trabeculae align themselves in the

direction of the imposed stress on a bone. The

presence of these trabeculae make

cancellous bone appear more porous. This makes it lighter in weight than compact bone, but still provides considerable

strength. However, it is not as strong as compact bone, so is more easily

fractured.

Wolff’s Law

http://www.uq.edu.au/~anmforwo/bl115/remodelling.html

These are two vertebrae.

The vertebrae are surrounded by an outer layer of cortical bone, and filled with cancellous bone.

However, the vertebral body on the right has lost some

trabeculae, and become compressed – resulting in a vertebral compression fracture.

These are two vertebrae.

The vertebrae are surrounded by an outer layer of cortical bone, and filled with cancellous bone.

However, the vertebral body on the right has lost some

trabeculae, and become compressed – resulting in a vertebral compression fracture.

This slide looks at the outer edge of this typical bone.

YellowYellow arrow – periosteum

YellowYellow dotted line – ‘cement’ lines surrounding an osteon

BlueBlue arrows - Haversian canal

GreenGreen arrows – osteocytes within their lacunae

This slide looks at the outer edge of this typical bone.

YellowYellow arrow – periosteum

YellowYellow dotted line – ‘cement’ lines surrounding an osteon

BlueBlue arrows - Haversian canal

GreenGreen arrows – osteocytes within their lacunae

We are now going to concentrate on the histology of compact bone.compact bone.

We are now going to concentrate on the histology of compact bone.compact bone.

http://neuromedia.neurobio.ucla.edu/campbell/bone/wp_frame.htm

The outer part of the compact bone is formed

by circumferential circumferential lamellaelamellae that

extend around the entire

circumference of the bone.

These are laid down under the periosteum AND periosteum AND the endosteumthe endosteum.

The outer part of the compact bone is formed

by circumferential circumferential lamellaelamellae that

extend around the entire

circumference of the bone.

These are laid down under the periosteum AND periosteum AND the endosteumthe endosteum.

Sometimes appear more‘blue’, depending upon

staining – comes from presence of chondroitin sulfate (a ‘GAG’ in the ground

substance)

Outer edge of compact bone.

GreenGreen arrows – outer circumferential lamellae

WhiteWhite arrows - osteocytes

Outer edge of compact bone.

GreenGreen arrows – outer circumferential lamellae

WhiteWhite arrows - osteocytes

OUTER EDGE

OUTER EDGE

PeriosteumPeriosteum

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-18%20Periosteum.jpg

The periosteumperiosteum

is a connective connective tissue layertissue layer on the outer surface of the bone.

The periosteumperiosteum

is a connective connective tissue layertissue layer on the outer surface of the bone.

PeriosteumPeriosteum

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-20%20Periosteum.jpg

At higher magnification,

you can see that the periosteumperiosteum consists of two

layers.

1. An outer fibrous layer of dense irregular

connective tissue, which is quite vascular (remember the

dermis?)

2. An osteogenic layer composed

primarily of osteoblasts. This layer is

CRUCIAL for the growth of bone.

At higher magnification,

you can see that the periosteumperiosteum consists of two

layers.

1. An outer fibrous layer of dense irregular

connective tissue, which is quite vascular (remember the

dermis?)

2. An osteogenic layer composed

primarily of osteoblasts. This layer is

CRUCIAL for the growth of bone.

Outer fibrous periosteum

Outer fibrous periosteum

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-21%20Outer%20Fibrous%20Periost.jpg

Sharpey’s Fibers

Sharpey’s Fibers

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-21%20Sharpey%27s%20Fibres.jpg

Sometimes you will see evidence

of Sharpey’s Sharpey’s fibersfibers at the level of the periosteum.

Sharpey’s fibersSharpey’s fibers reflect the sites of the ‘ends’ of

tendons or ligaments as

their collagen fibers extend

deeply into the bone for secure

attachment.

Sometimes you will see evidence

of Sharpey’s Sharpey’s fibersfibers at the level of the periosteum.

Sharpey’s fibersSharpey’s fibers reflect the sites of the ‘ends’ of

tendons or ligaments as

their collagen fibers extend

deeply into the bone for secure

attachment.

The inner part of the bone is lined by an

endosteum.

BlueBlue arrows - osteocyteYellowYellow arrows - endosteumGreenGreen arrow - marrow cavity

The inner part of the bone is lined by an

endosteum.

BlueBlue arrows - osteocyteYellowYellow arrows - endosteumGreenGreen arrow - marrow cavity

Marieb; Fig. 6.4

So now let’s take a look at the

“structural unit” of this compact bone.

This structural unit is called either an

osteonosteon or an Haversian systemHaversian system.

So now let’s take a look at the

“structural unit” of this compact bone.

This structural unit is called either an

osteonosteon or an Haversian systemHaversian system.

http://neuromedia.neurobio.ucla.edu/campbell/bone/wp_frame.htmMarieb; Fig.

6.5

Marieb; Fig. 6.6

Interstitial system

Interstitial system

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-19%20Interstit.

%20System.jpg

So what are the names of the

three different lamellae in this compact bone?

So what are the names of the

three different lamellae in this compact bone?

Circumferential Circumferential lamellaelamellae that are located just deep to the periosteum

AND to the endosteum

Circumferential Circumferential lamellaelamellae that are located just deep to the periosteum

AND to the endosteum

Concentric Concentric lamellaelamellae that make up the osteons or Haversian systems

Concentric Concentric lamellaelamellae that make up the osteons or Haversian systems Interstitial Interstitial

lamellaelamellae that are usually remnants

of old osteons

Interstitial Interstitial lamellaelamellae that are usually remnants

of old osteons

YellowYellow arrows – osteons or Haversian systems

YellowYellow arrows – osteons or Haversian systems

BlueBlue arrows – Haversian canals which house the blood supply to the osteocytes

YellowYellow dotted lines – concentric lamellae WhiteWhite dotted line – interstitial lamellae (remnants of old osteons)

GreenGreen dotted line – ‘cement’ line that reflects the outer border of the osteon

WhiteWhite arrows – osteocytes residing in lacunae

BlueBlue arrows – Haversian canals which house the blood supply to the osteocytes

YellowYellow dotted lines – concentric lamellae WhiteWhite dotted line – interstitial lamellae (remnants of old osteons)

GreenGreen dotted line – ‘cement’ line that reflects the outer border of the osteon

WhiteWhite arrows – osteocytes residing in lacunae

‘Cement’ line

‘Cement’ line

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-19%20Cementing%20Line.jpg

Haversian Canal

Haversian Canal

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-18%20Haversian%20Canal.jpg

Close-up of an Haversian

canal

Close-up of an Haversian

canal

BlueBlue arrows – outlining osteon or Haversian system

RedRed arrows – Volkmann’s canal (These canals run perpendicular to the Haversian systems or to the long axis of the bone. They connect the blood and nerve supply of the periosteum and endosteum to those in the central Haversian canals.)

BlueBlue arrows – outlining osteon or Haversian system

RedRed arrows – Volkmann’s canal (These canals run perpendicular to the Haversian systems or to the long axis of the bone. They connect the blood and nerve supply of the periosteum and endosteum to those in the central Haversian canals.)

Volkmann’s Canal

Volkmann’s Canal

BlueBlue arrow – osteocyte within its lacunae

YellowYellow arrows – canaliculi

BlueBlue arrow – osteocyte within its lacunae

YellowYellow arrows – canaliculi

What is the role of the canaliculi?

Remember that as the osteoblast has finished its

work, the osteocyte is now surrounded by

several concentric layers of calcified bone. In order to receive nutrients, the osteocytes communicate with other osteocytes via gap junctionsgap junctions by sending

cellular projections through these tiny

tunnels in the bone called canaliculicanaliculi.

Remember that as the osteoblast has finished its

work, the osteocyte is now surrounded by

several concentric layers of calcified bone. In order to receive nutrients, the osteocytes communicate with other osteocytes via gap junctionsgap junctions by sending

cellular projections through these tiny

tunnels in the bone called canaliculicanaliculi.

Two Broad Classifications of

Bone Cells

Two Broad Classifications of

Bone Cells

OsteoblastsOsteoblastsOsteoblastsOsteoblasts OsteoclastsOsteoclastsOsteoclastsOsteoclasts

Bone lining cellsBone lining cells - inactive

osteoblasts that exist on resting bone surfaces

Bone lining cellsBone lining cells - inactive

osteoblasts that exist on resting bone surfaces

OsteoblastsOsteoblasts – active in bone

formation

OsteoblastsOsteoblasts – active in bone

formation

OsteocytesOsteocytes – osteoblasts that

have become ‘encased’ in osteoid

OsteocytesOsteocytes – osteoblasts that

have become ‘encased’ in osteoid

Note – most of this information on

bone cell types is NOT

in your textbook!

OsteoclastOsteoclast

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-22%20Osteoclast%2C%20High%20Mag.jpg

OsteoclastsOsteoclasts

1. main resorbing cell (engulf collagen,

mineral, and osteocytes)

2. large, multinucleated,

and mobile

3. ruffled border

4. often reside in depressions

called Howship’s lacunae

OsteoclastsOsteoclasts

1. main resorbing cell (engulf collagen,

mineral, and osteocytes)

2. large, multinucleated,

and mobile

3. ruffled border

4. often reside in depressions

called Howship’s lacunae

OsteoclastOsteoclast

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/II-6%20Osteoclast%2C%20High%20Mag.jpg

Multinucleated osteoclast

Multinucleated osteoclast

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-22%20Osteoclast%2C%20Low%20Mag.jpg

OsteoblastOsteoblast

OsteoblastsOsteoblasts

1. main bone forming cell –

secretes osteoid (osteoid is

nonmineralized matrix)

2. much smaller than osteoclasts,

mononucleated, and usually somewhat

cuboidal

OsteoblastsOsteoblasts

1. main bone forming cell –

secretes osteoid (osteoid is

nonmineralized matrix)

2. much smaller than osteoclasts,

mononucleated, and usually somewhat

cuboidal

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-22%20Osteoblasts.jpg

Osteoblast (mononucleat

ed)

Osteoblast (mononucleat

ed)

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/II-6%20Osteoblast%2C%20High%20Mag.jpg

BlueBlue arrows – osteoblasts



YellowYellow arrows – osteoid (freshly laid down bone that has not yet been mineralized)


YellowYellow arrows – osteoid (freshly laid down bone that has not yet been mineralized)

OsteocyteOsteocyte

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-20%20Osteocyte.jpg

OsteocyteOsteocyte

1. most abundant bone cell type

2. reside within lacunae

3. have cytoplasmic extensions that

communicate with other osteocytes via

gap junctions in canaliculi

OsteocyteOsteocyte

1. most abundant bone cell type

2. reside within lacunae

3. have cytoplasmic extensions that

communicate with other osteocytes via

gap junctions in canaliculi

Osteocyte in a lacuna

Osteocyte in a lacuna

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-18%20Osteocyte%20Lacuna.jpg

So, how do these skeletal elements develop?

Remember those undifferentiated mesenchymalmesenchymal cells that we talked about in Chapter 4? Well, some of these cells

differentiate directly into osteoblastic cells (intramembranous intramembranous ossificationossification); while others differentiate into chondrocyteschondrocytes which

then develop into a hyalinehyaline cartilaginous skeleton. Subsequently, this cartilage will be replaced by bone.

(endochonral ossificationendochonral ossification).

So, how do these skeletal elements develop?

Remember those undifferentiated mesenchymalmesenchymal cells that we talked about in Chapter 4? Well, some of these cells

differentiate directly into osteoblastic cells (intramembranous intramembranous ossificationossification); while others differentiate into chondrocyteschondrocytes which

then develop into a hyalinehyaline cartilaginous skeleton. Subsequently, this cartilage will be replaced by bone.

(endochonral ossificationendochonral ossification).

Marieb; Fig. 4.5

Bony Skeleton Formation

Intramembranous Intramembranous OssificationOssification

Bone develops directly from fibrous

membrane

1. cranial bones of skull

2. diaphysis of clavicle

3. ALSO contributes to the growth of short bones and thickening

of long bones

Endochondral Endochondral OssificationOssification

Bone develops by replacing hyaline

cartilage

1. all bones of skeleton below base

of skull EXCEPT clavicles

Bone tissue arises by one of two means: (1) intramembranous intramembranous ossificationossification, or, (2) endochondral ossificationendochondral ossification. In either case, the original or model tissue is gradually destroyed and replaced with

bone tissue.

Bone tissue arises by one of two means: (1) intramembranous intramembranous ossificationossification, or, (2) endochondral ossificationendochondral ossification. In either case, the original or model tissue is gradually destroyed and replaced with

bone tissue.

PROCESSES THAT DESIGN AND REDESIGN PROCESSES THAT DESIGN AND REDESIGN BONEBONE

PROCESSES THAT DESIGN AND REDESIGN PROCESSES THAT DESIGN AND REDESIGN BONEBONE

GrowthGrowth

Occurs during childhood and the early years of adulthood

when the skeleton grows in length and diameter to

achieve characteristic external shape

ModelingModeling

Alters the shape and overall bone

architecture during growth and functional

adaptation; results when

osteoblasts and osteoclasts work independently of

one another, and on different surfaces;

results in increased bone mass

RemodelingRemodeling

Osteoblasts and osteoclasts work

closely together to renew old bone of

inferior quality and replace bone

with micro-fractures; ensures

maintenance of calcium

homeostasis; generally results

in decreased bone mass

So, how does a long bone reach its mature form?

Primarily by endochondral endochondral ossificationossification.

Marieb; Fig. 6.8

What is a distinct difference in the composition of CARTILAGE AND BONE?

BONEBONE

CellsOsteoblasts/cytes

CellsOsteoblasts/cytes

Extracellular MatrixCalcified by deposition of bone salts

Extracellular MatrixCalcified by deposition of bone salts

CARTILAGECARTILAGE

CellsChondroblasts/cytes

CellsChondroblasts/cytes

Extracellular MatrixContains considerable fluid (80% water)

Extracellular MatrixContains considerable fluid (80% water)

largely avascular

highly vascular

So, take a look at these slides of hyaline cartilage

(a), surrounded by a perichondrium (b), and

filled with chondrocytes in lacumae (c). The

chondroblasts (d) are more flattened, and lie just deep

to the perichondrium. Hopefully, this looks very similar to the bone tissue

from several of the previous slides in this

tutorial.

So, take a look at these slides of hyaline cartilage

(a), surrounded by a perichondrium (b), and

filled with chondrocytes in lacumae (c). The

chondroblasts (d) are more flattened, and lie just deep

to the perichondrium. Hopefully, this looks very similar to the bone tissue

from several of the previous slides in this

tutorial.

http://www.louisville.edu/medschool/anatomy/histology/cbj/cbj_img/B_2a.JPG

b

c

d

d

http://anatomy.iupui.edu/courses/histo_D502/D502f03/f03_labs/Lab8/s4840xb1.jpg

http://anatomy.med.unsw.edu.au/cbl/embryo/wwwhuman/Stages/Stage15.htm

Developing limb buds

There is clearly a parallel between the two basic layers of the periosteumperiosteum (see slide 16) and the two layers of the

perichondriumperichondrium. You should be able to picture the chondroblastschondroblasts undergoing mitosis to provide for the growth

of the cartilage skeletoncartilage skeleton in this embryo.

There is clearly a parallel between the two basic layers of the periosteumperiosteum (see slide 16) and the two layers of the

perichondriumperichondrium. You should be able to picture the chondroblastschondroblasts undergoing mitosis to provide for the growth

of the cartilage skeletoncartilage skeleton in this embryo.

http://neuromedia.neurobio.ucla.edu/campbell/cartilage/wp_images/

176_4.gif

You start out with a ‘model’ for the bone made out of hyaline cartilage.

Some of the cells in the center of the model will be growing. They will also be secreting a matrix which will begin to calcify. Also, a collar of bone forms by intramembranous ossificationintramembranous ossification around the diaphysis of the cartilage model which prevents the diffusion of nutrients to the underlying chondroblasts and chondrocytes.

Now the cells in the ‘encased’ cartilaginous matrix will beome larger (hypertrophic), begin to deteriorate and will eventually die, creating a cavity. This cavity, and the immediate surrounding area is called the primary ossification center. (The primary ossification centers of all bones are present at birth.)

Diaphyseal nutrient vessels penetrate the periosteum and invade the cavity. These vessels are the most important supply of arterial blood to a long bone. Usually one or two principal nutrient arteries enter the diaphysis, and then divide into ascending and descending branches to ultimately supply the inner two thirds of the cortex and medullary cavity. Remember, bone has a rich vascular supply, which assists in its regenerative capabilities.

Blood vessels invade the epiphyses, usually arising from the nearby joint.

The primary ossification center continues to expand longitudinally. Bone is being laid down on the remnants of the cartilaginous matrix.

A secondary ossification centersecondary ossification center is established in the epiphyses, which will allow for ossification of these regions of the bone. (Most secondary ossification centers appear after birth.)

An epiphyseal plateepiphyseal plate is formed between each epiphysis and the diaphysis. This region is often called the “physis”, and is the region separating the epiphysis from the metaphysis. It is the zone of endochondral ossificationendochondral ossification in an actively growing bone or the site of an epiphyseal scar in a fully-grown bone.

What do the following colors represent in the above figures?

Hya

line

cartila

ge

Calcifi

ed b

one

Medulla

ry

cavity

Endoste

um

Perio

steum

Dia

physe

al

nutrie

nt

arte

ries

Epip

hyse

al

arte

ries

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-24%20Endochond.%20Oss%27n.jpg

Lets take a closer look at the epiphyseal cartilage.

Lets take a closer look at the epiphyseal cartilage.

How would you describe its location?

It is located between the

epiphysis and the metaphysis.

It is located between the

epiphysis and the metaphysis.

For what type of growth is it largely responsible?

The epiphysis is largely

responsible for longitudinal

growth of bone.

The epiphysis is largely

responsible for longitudinal

growth of bone.

ephiphysi

ephiphysiss

metaphys

metaphysisis

Blue Blue brackets – bone collar

RedRed dotted line – epiphysis

YellowYellow dotted line – metaphysis BlackBlack arrow – bone formed from endochondral ossification

WhiteWhite arrow – hyaline cartilage

Blue Blue brackets – bone collar

RedRed dotted line – epiphysis

YellowYellow dotted line – metaphysis BlackBlack arrow – bone formed from endochondral ossification

WhiteWhite arrow – hyaline cartilage

Epiphyseal cartilage is usually described as consisting of five zones.

Epiphyseal cartilage is usually described as consisting of five zones.

1. A resting zoneresting zone of small chondrocytes, also called the reserve zone. This is the

zone where growth begins

1. A resting zoneresting zone of small chondrocytes, also called the reserve zone. This is the

zone where growth begins

2. A proliferative zoneproliferative zone of rapidly dividing chondrocytes.

2. A proliferative zoneproliferative zone of rapidly dividing chondrocytes.

3. An hypertrophic zonehypertrophic zone of large chondrocytes, where they are maturing and degenerating. Their matrix is also

being resorbed.

3. An hypertrophic zonehypertrophic zone of large chondrocytes, where they are maturing and degenerating. Their matrix is also

being resorbed.

4. A calcified zonecalcified zone where the chondrocytes die as they calcify the matrix around them, which will be

followed by blood vessel invasion and the deposition of bone on the calicified

cartilage.

4. A calcified zonecalcified zone where the chondrocytes die as they calcify the matrix around them, which will be

followed by blood vessel invasion and the deposition of bone on the calicified

cartilage.

5. An resorptionresorption or ossification zoneossification zone where osteoid is laid down and

mineralized.

5. An resorptionresorption or ossification zoneossification zone where osteoid is laid down and

mineralized.

ephiphysephiphysisis

metaphymetaphysissis


ephiphysephiphysisis

metaphymetaphysissis


one cell in the reserve one cell in the reserve cartilage divided to cartilage divided to

produce all of the cells in produce all of the cells in one stack of the one stack of the

proliferative zoneproliferative zone

where chondrocytes where chondrocytes are rapidly are rapidly

reproducing, making reproducing, making this zone look like this zone look like

stacked coinsstacked coins

where chondrocytes are where chondrocytes are swelling to a more spherical swelling to a more spherical

shapeshape


where chondrocytes where chondrocytes are rapidly are rapidly

reproducing, making reproducing, making this zone look like this zone look like

stacked coinsstacked coins

where chondrocytes are where chondrocytes are swelling to a more spherical swelling to a more spherical

shapeshape

empty lacunaeempty lacunae


Zone of hypertrophyZone of hypertrophy

Zone of calcification Zone of calcification and cell deathand cell death

Zone of proliferationZone of proliferation

Zone of resorptionZone of resorption

Zone of calcificationZone of calcification

GreenGreen arrows – zone of resting or reserve cartilage

BlueBlue arrows – zone of proliferation

YellowYellow dotted line – stack of “coins” in proliferative zone BlackBlack arrow – zone of hypertrophy

BlueBlue dotted linedotted line – group of “swollen” cells in zone of hypertrophy

GreenGreen arrows – zone of resting or reserve cartilage

BlueBlue arrows – zone of proliferation

YellowYellow dotted line – stack of “coins” in proliferative zone BlackBlack arrow – zone of hypertrophy

BlueBlue dotted linedotted line – group of “swollen” cells in zone of hypertrophy

RedRed arrows – zone of calcification (making blue ground substance look somewhat darker than in previous slide)

YellowYellow arrows – calcified cartilage of zone of calcification Purple arrow – This cell is not as clear as the cells surrounded by the blue dotted line in the previous slide. Because of being suffocated within their calcified matrix, the cells lyse and release their lysosomes.

White arrowsWhite arrows – bone being laid down by osteoblasts

RedRed arrows – zone of calcification (making blue ground substance look somewhat darker than in previous slide)

YellowYellow arrows – calcified cartilage of zone of calcification Purple arrow – This cell is not as clear as the cells surrounded by the blue dotted line in the previous slide. Because of being suffocated within their calcified matrix, the cells lyse and release their lysosomes.

White arrowsWhite arrows – bone being laid down by osteoblasts

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-23%20Growth%20Pl.%20Alc.

%20Bl.jpg

Epiphyseal growth plate

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-24%20Growth%20Plate.jpg


http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-23%20Growth%20Pl.jpg


Marieb; Fig. 6.10

You will note that during growth, the epiphyseal plate normally does not change in thickness because the rates of proliferation and destruction are approximately equal. The epiphyseal plate is simply ‘moved away’ from the diaphysis

as the bone grows in length.

You will note that during growth, the epiphyseal plate normally does not change in thickness because the rates of proliferation and destruction are approximately equal. The epiphyseal plate is simply ‘moved away’ from the diaphysis

as the bone grows in length.

Now lets take a brief look at intramembranous ossificationintramembranous ossification.

Marieb; Fig. 6.7

Intramembranous ossificationIntramembranous ossification.


This is a picture of the scalp – so the upper

half is epithelium with numerous hair follicles. The

developing flat cranial bone is in the lower

half.

This is the same picture as the previous

slide at higher magnification. The

developing bone is in the lower half, represented by irregular purple

spicules.

This is the same picture as the previous slide at even higher

magnification.

This is the same picture as the previous slide focusing on one of the spicules.

Note that it has no Haversian systems or osteons.

http://www.usask.ca/anatomy/teaching/anat232/Bonejpg/I-22%20Intramembr.%20Oss%27n.jpg

Intramembranous ossificationIntramembranous ossification.

Hopefully, you can now

1. compare and contrast the anatomy of a typical long bone and flat bone,

2. compare and contrast the histology of compact and spongy bone, and

3. compare and contrast intramembranous and endochondral ossification.

marieb; fig. 6.1 do you know the four bone classifications? long bone short bone flat bone irregular...

Documents

typical bone

bone classifications

type of bone

lacunae compact bone

density of compact bone

histology of compact

trabeculae spongy bone

bone construction spongy