Measures of Central Tendency: Mean, Median and Mode
Growth plate and Bone development.pptx
1. Growth plate and Bone
development
By Almaw B.(ortho R1)
Moderator Dr. Zerihun T.( orthopedic
and trauma surgeon)
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2. .
Out lines
o Introduction
o Definition of growth and development
o Embryology
o Bone development
o Histogenesise of bone
o Growth plate
o Summary
o references
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3. Introduction
During normal development, cells proliferate,
undergo differentiation,
move and even in some cases die in order to
produce a normal, mature individual.
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4. Bone primarily develops in two types of
connective tissue, mesenchyme and cartilage
Bones are formed by osteogenesis.
The mandible and clavicle are first formed
starting in the seventh gestational week by
intramembranous ossification
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5. At end of 4th week sclerotom become
polymorphous,
it forms loosen woven tissue,mesenchyme or
embroyonic connective tissue
Mesenchyme cell migrate and differentiate
into fibroblast,chondroblast and osteoblast
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6. Defention
Growth refers; to an increase in an individual's
total body size
increase in the physical size of a particular
organ or organ system.
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8. Development
The physical changes of maturation
Primarily involves changes in function that
transform humans into increasingly more
complex beings.
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9. influenced by many interrelated factors
genetics
physical trauma
nutrition
socioeconomic status.
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16. • Ninth to twelfth weeks The first bone ossify.
• The skeleton develops in a cranial to caudad
sequence.
• Thirteenth to twentieth weeks Growth
continues to be rapid.
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17. Bone development
Historical back ground
1727 in exprment S.Hales observed that long
bone developed at bone end.
1858 description epiphyseal plate H.Muller
1873 A.Kolliker discover osteoclast
1958 J.Truat blood supply epiphysise
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18. Bone development
Cells that produce bone matrix are called
osteoblasts.
They are along with osteocytes, are the
predominant bone-forming cells.
They synthesize type I collagen, alkaline
phosphatase, osteocalcin, and bone
sialoprotein and are responsive to parathyroid
hormone.
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19. The cytoplasm of the cell is geared toward
protein synthesis
composed primarily of the nucleus, rough
endoplasmic reticulum, and the Golgi
apparatus .
Once a mineralized bone matrix surrounds
osteoblasts, the osteoblast becomes an
osteocyte.
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20. The cellular composition of the osteocyte
changes with a reduction in the amount of
rough endoplasmic reticulum
Increase in the nucleus-to-cytoplasm ratio
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21. Mesodermal cells give rise to mesenchyme-a
meshwork of loosely organized embryonic
connective tissue.
Bones first appear as condensations of
mesenchymal cells that form bone models.
Condensation marks the beginning of selective
gene activity, which precedes cell
differentiation
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22. Most flat bones develop in mesenchyme
within preexisting membranous sheaths.
Mesenchymal models of most limb bones are
transformed into cartilage bone models,
which later become ossified by endochondral
bone formation.
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26. Histogenesis of Bone
Bone primarily develops in two types of
connective tissue
mesenchyme
cartilage
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27. Intramembranous Ossification
This type of bone formation occurs in
mesenchyme that has formed a membranous
sheath.
commonly known as contact healing, and
Haversian remodeling
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28. Steps of intramembranous bone formation
aggregation mesenchymal cells
osteoblast differentiation
organic matrix deposition
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30. IT condenses and becomes highly vascular
Begin Deposit unmineralized matrix-osteoid.
Calcium phosphate is then deposited in the
osteoid tissue as it is organized into bone.
Bone osteoblasts are trapped in the matrix
and become osteocytes.
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31. At first, new bone has no organized pattern
Spicules of bone soon become organized and
coalesce into lamellae.
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32. Concentric lamellae develop around blood
vessels, forming osteons .
osteoblasts remain at the periphery of the
developing bone, it form plate
This spongy environment is somewhat
accentuated by the action of cells-osteoclasts
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33. Osteoclasts are multinucleated cells with a
hematopoietic origin.
In the interstices of spongy bone, the
mesenchyme differentiates into bone
marrow.
During fetal and postnatal life, there is
continuous remodeling of bone .
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34. Examples of intramembranous ossification
embryonic flat bone formation
skull, maxilla,
mandible, pelvis, clavicle
subperiosteal surface of long bone
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35. distraction osteogenesis bone formation
blastem bone
fracture healing with rigid fixation
one component of healing with
intramedullary nailing
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37. Endochondral Ossification
the most common mechanism of ossification
The process begins with the formation of a
cartilage precursor or template.
longitudinal physeal growth
embryonic long bone formation
non-rigid fracture healing .
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38. Steps of formation are
vascularization
primary ossification centers
cartilage model
marrow
secondary ossification centers
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40. At sixth week mésenchymes celles
differentiate, condense
it transform into chondrocytes to form a
model of the future skeleton.
chondrocytes hypertrophy and begin to
calcify
At 7th week a periosteal sleeve of bone is
formed
At eighth week, vascularization is under way
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41. During the fetal period, primary ossification
centers develop in long bones with diaphysis .
Ossification first occurs under perichondrium.
Within the cartilage, hypertrophied cells
degenerate.
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42. vascular in growth occurs, then the core of the
cartilage model is ossified to form the primary
ossification center.
Endochondral ossification proceeds at the
cartilage–bone.
secondary ossification centers develop at the
ends of the bones
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43. the cartilage interposed between the primary
and secondary ossification centers becomes
the growth plate.
Except for the clavicle, all bones of the axial
and appendicular skeleton , cartilage and
converted to bone by enchondral ossification.
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44. It begins in the scapula, humerus, radius, and
ulna.
Ossification continues in an orderly fashion,
with centers appearing at different ages.
Ossification of limb bones begins at the end
of the embryonic period
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45. thereafter makes demands on the maternal
supply of calcium and phosphorus
Secondary ossification centers appear in the
epiphyses in most bones during the first few
years after birth
Ossification is earlier in girls than boys
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48. Growth Plate
The growth plate of long bones develops
between the primary and secondary
ossification centers.
The growth plate is responsible for the
longitudinal growth of long bones.
Growth plate chondrocytes proliferation and
differentiation terminal differentiation and the
formation of new bone.
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49. Growth plates with more limited growth
potential develop at other sites
the periphery of round bones;
the tarsal bones or vertebral bodies
the sites of muscle attachments, the margins
of the ilium. Called apophyses.
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50. The typical long bone epiphysis is divided into
zones that reflect
morphological
metabolic
functional differences.
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52. The Reserve Zone
It is adjacent to the secondary ossification
centers and is a zone of relative inactivity.
does not participate in the longitudinal
growth of the bone,
Provides matrix production and storage
functions.
It contains proteins and genes important in
specifying the chondrocyte phenotype,SOX–9.
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54. The Proliferative Zone
This is the zone of cartilage cell replication and
growth.
A high metabolic rate and abundant blood
supply, oxygen, glycogen, ATP and collagen
make this rapid growth possible.
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55. Signaling pathways, important in regulating
cell proliferation, are found in this zone.
insulin-like growth factors
fibroblastic growth factors
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56. The Hypertrophic Zone (HZ)
Three sub-zones:
maturation
degeneration
provisional calcification segments.
The cartilage cells increase in size and the
matrix is prepared for calcification.
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57. It associated with a decline in blood supply,
oxygenation, and glycogen stores
It disintegration of aggregated
mucopolysaccharides and chondrocytes.
provisional calcification, a unique collagen X
that accepts calcium deposition is synthesized
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58. The Metaphysis
It is the site of vascularization, bone
formation, and remodeling.
The calcified matrix is removed, and fiber
bone is formed and replaced by lamellar bone.
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59. The Periphery
The growth plate and metaphysis, which are
the primary sites for
infections
Neoplasms
fractures, metabolic and endocrine disorders.
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60. Growth Plate Types
Growth plates form in a number of patterns,
depending upon the shape of the bone.
Epiphyseal plate;at the end of long
bones,longitudinal growth.
Ring epiphyses ; surround round bones, the
tarsals or metatarsals,it grow
circumferentially.
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61. . Apophyses are growth plates applied to the
surface of a bone, the iliac crest.
Traction apophyses are growth plates,muscle
is attached. E.g the tibial tubercle and greater
trochanter.
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67. Summary
• During normal development, cells proliferate,
undergo differentiation,
• Bone primarily develops in two types of
connective tissue, mesenchyme and cartilage
• intramembranous ossification of bone
formation occurs in mesenchyme that has
formed a membranous sheath.
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68. • The growth plate of long bones develops
between the primary and secondary
ossification centers
• The growth plate is responsible for the
longitudinal growth of long bone
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69. Reference
• The developing human clinical oriented
embyology 8th edition
• Ortho bullet
• Langman medical embryology 8th edition
• TACHDJIN S pediatric orthopedic 5th edtion
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