DDS 513: Patient Assessment I
Skeleton Development-I
Image: http://www.gifs-animados.es/
Instructor
Dr. Nazlee Sharmin
Assistant Teaching Professor
5-533, Edmonton Clinic Health Academy (ECHA)
Email: nazlee@ualberta.ca
Review and Overview
◼
Prenatal Development
◼ Oral Development: Tongue, palate etc.
◼ NCC
◼ Regulation
Today..
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Bone Development
– Bone structure
– Bone cells
– Bone development
Bone
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Bone is a specialized form of connective tissue.
Ten Cate’s Oral Histology, 9th Edition
Bone
Macroscopic Compact / Cortical
appearance
Mature bone; flat bones
and shaft of long bones
Spongy/cancellous/trabecular Early embryonic bone;
interior of extremities of
long bones
Bone Cells
Bone Cells. Four types of cells are found within bone tissue.
https://opentextbc.ca/anatomyandphysiology/chapter/6
The osteoblast is the bone cell responsible for forming new
bone and is found in the growing portions of bone, including
the periosteum and endosteum. Osteoblasts, which do not
divide, synthesize and secrete the collagen matrix and calcium
salts.
https://opentextbc.ca/anatomyandphysiology/chapter/6
As the secreted matrix surrounding the osteoblast calcifies, the
osteoblast become trapped within it; as a result, it changes in structure
and becomes an osteocyte, the primary cell of mature bone and the
most common type of bone cell. Like osteoblasts, osteocytes lack
mitotic activity. They can communicate with each other and receive
nutrients via long cytoplasmic processes.
https://opentextbc.ca/anatomyandphysiology/chapter/6
The osteogenic cells are undifferentiated with high mitotic
activity and they are the only bone cells that divide. Immature
osteogenic cells are found in the deep layers of the periosteum
and the marrow. They differentiate and develop into osteoblasts.
https://opentextbc.ca/anatomyandphysiology/chapter/6
The dynamic nature of bone
means that new tissue is
constantly formed, and old, injured,
or unnecessary bone is dissolved
for repair.
The cell responsible for bone resorption, or breakdown, is
the osteoclast. They are found on bone surfaces, are
multinucleated, and originate from monocytes and
macrophages, two types of white blood cells. Osteoclasts are
continually breaking down old bone while osteoblasts are
continually forming new bone.
https://opentextbc.ca/anatomyandphysiology/chapter/6
Bone Cells
could amke into anki
Cell type
Function
Location
Osteogenic cells
Develop into
osteoblasts
Deep layers of the
periosteum and the
marrow
Osteoblasts
Bone formation
Growing portions of
bone, including
periosteum and
endosteum
Osteocytes
Maintain mineral
concentration of matrix
Entrapped in matrix
Bone resorption
Bone surfaces and at
sites of old, injured, or
unneeded bone
Osteoclasts
Bone Cells (Histology)
The abundance of large
osteocytes entrapped in the
bone and the presence of
numerous osteoclasts
indicates that the bone
trabeculae are being formed
and turned over rapidly.
osteoclast is multi nucleated so u
can see it here
osteocyte would be in the blue since
trapped in matrix
Ten Cate’s Oral Histology, 9th Edition
Bone Cells (Histology)
osteocyte
http://www.siumed.edu/~dking2/ssb/NM006b.htm
Bone: Histology
◼
Mature or adult bones, whether compact or trabecular, are
histologically identical in that they consist of microscopic
layers or lamellae.
Three distinct types of
layering are recognized:
Circumferential,
Concentric, and
Interstitial.
Ten Cate’s Oral Histology, 9th Edition
Bone: Histology
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Circumferential lamellae enclose the entire adult bone,
forming its outer and inner perimeters.
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Concentric lamellae make up the bulk of compact bone
and form the basic metabolic unit of bone, the osteon
(also called the haversian system).
◼
Interstitial lamellae are interspersed between adjacent
concentric lamellae and fill the spaces between them.
Interstitial lamellae are actually fragments of preexisting
concentric lamellae from osteons created during
remodeling that can take a multitude of shapes.
Structure of compact bone
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Basic Functional Unit: Osteon(the haversian system)
The basic units of compact bone are called osteons or
Haversian systems. These are cylinder-shaped structures
that have a mineral matrix and are home to osteocytes
(mature bone cells) that are trapped in the matrix.
spongy bone wont have this
https://courses.lumenlearning.com/ap1x94x1/chapter/compact-bone-spongy-bone-and-other-bone-components/
◼
Concentric Lamellae are formed by osteons that align
themselves in a parallel orientation to form layers along the
long axis of the bone. The small open spaces created in the
lamellae by the osteocytes are called lacunae. Canaliculi are
small channels that create a network between the lacunae to
aid in the diffusion of material between the bone cells. The
lamellae create circular canals called Haversian canals that
contain nerves and blood vessels.
https://courses.lumenlearning.com/ap1x94x1/chapter/compact-bone-spongy-bone-and-other-bone-components/
https://en.wikipedia.org/wiki/Osteon
The osteon consists of
concentric lamellae that form a
cylinder of bone with a vascular
canal—the haversian canal—at
its center. Numerous
osteocytes are entrapped in
these lamellae. These cells
reside in lacunae and their
processes in interconnecting
canaliculi that form an extensive
network for the diffusion of
nutrients and the transduction
of local bone status.
Ten Cate’s Oral Histology, 9th Edition
Spongy Bone
https://courses.lumenlearning.com/ap1x94x1/chapter/compact-bone-spongy-bone-and-other-bone-components/
◼
Body of the mandible. The
outer layer of compact
bone and an inner
supporting network of
trabecular bone can be
distinguished clearly.
Ten Cate’s Oral Histology, 9th Edition
might not need to mem, just says would help u
Bone Terminology
osteon also forms
Woven Bone: The first embryonic bone
once it matures, the connect tissue is not loose no more
Light micrograph of woven bone. This bone exhibits high vascularity, soft
tissue content, and bone cellularity. B, Light micrograph of older alveolar
bone. This section exhibits primary osteons, less bone cellularity, and
loose connective tissue.
Ten Cate’s Oral Histology, 9th Edition
early form
later form
Ten Cate’s Oral Histology, 9th Edition
The organization of collagen and the various lamellae are seen
readily using phase-contrast microscopy (A, B, D). A, Embryonic
(woven) bone is characterized by randomly oriented collagen
fibrils. B to F, Collagen fibrils in lamellar bone assume a layered
organization including circumferential, concentric, and interstitial
lamellae. Interstitial lamellae are interspersed between osteons;
these represent fragments of preexisting concentric lamellae.
Circumferential lamellae enclose the inner (D) and outer (E,
F) aspects of bone.
Ten Cate’s Oral Histology, 9th Edition
more intersted in when it is devleoping, idk if need to know all of the last slide
Embryonic (woven) bone
A, Embryonic (woven) bone is characterized by randomly
oriented collagen fibrils. B to F, Collagen fibrils in lamellar
bone assume a layered organization including
circumferential, concentric, and interstitial lamellae.
when devleoped, gets collagen fibers
organzied and then mienralized
Ten Cate’s Oral Histology, 9th Edition
Osteogenesis
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Osteogenesis is the process of bone formation
Image: Internet
Bone Cell Formation
◼
Large numbers of cells must be recruited continuously to
maintain the structural integrity of bone. Interference with
recruitment mechanisms can cause pathologic conditions.
◼
Bone-forming cells have a mesenchymal origin, whereas
that of osteoclasts is hematopoietic. Differentiation of both
cell types is a multistep process that is stimulated by a
unique set of cytokines, growth factors, and hormones
that are part of complex signal transduction pathways.
2. respond to signal and then become osteoblast
1. transcirption factor
should know what
factors make it
into osteroclast
and blast
same here
Ten Cate’s Oral Histology, 9th Edition
Origin of bone cells. BMPs, Bone morphogenetic
proteins; FGFs, fibroblastic growth factors; MCSF, macrophage colony-stimulating
factor; OPG, osteoprotegerin; RANK, receptor-activated
nuclear factor κB; RANKL, receptor-activated nuclear factor
κB ligand; SOX, Sry-related HMG box)TRAP, tartrate-resistant
acid phosphatase.
she said make sure
we know the
names, all the
names???
Ten Cate’s Oral Histology, 9th Edition
Bone Development and Formation
◼
Although histologically one bone is no different from
another, bone formation occurs by three main
mechanisms:
• Endochondral,
• Intramembranous,
• Sutural.
◼
Endochondral bone formation takes place when cartilage
is replaced by bone. Intramembranous bone formation
occurs directly within mesenchyme. Bone formation along
sutural margins is a special case.
What you need to know
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Bone structure
Bone histology (micro anatomy)
Bone cells
Embryonic bone
Bone formation (Introduction)