Bone Cells and Matrix
Formation of Bone
Intramembranous Ossification
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Endochondral OssificationReorganisation and Restoration of Bone
STRUCTURE OF LONG BONE
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BASED ON BONE MATURITY
Lamellar bone
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WOVEN BONELAMELLAR BONE
? Lamellar appearance - arrangement of collagen fibres
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? Woven bone is weak- repair of fracture
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TYPES OF BONE : macroscopically
Trabecular bone :
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?Cancellous or spongy bone?Ends of long bones
Compact bone:
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?Forms thick-walled tube of the shaft (or diaphysis)?A thin layer of compact bone also covers the
epiphyses of long bones.
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COMPACT BONE?Matrix
?Lamellae*
?Lacunae
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?Canaliculi?Haversian Canals
COMPACT BONE- UNSTAINED
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?Haversian system - Osteon?Interstitial lamellae
?Circumferential lamellae
?Endosteal lamellae
?Volkmann's Canals
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COMPACT BONE
Schmorl Stained
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TRABECULAR BONENo Haversian systems
PAGET'S DISEASE
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Woven bone and Lamellar bone in disorganised mannerBONE MATRIX
?Collagen fibres (about 90% of the organic substance)
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?Ground substance- osteonectin, osteocalcin?Collagen type I
?Hardness of the matrix - inorganic salts
?Calcification - few days to several months.
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BONE CELLS?Osteoprogenitor cells (stem cells)
?Osteoblasts (or bone forming cells)
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?Osteocytes
?Osteoclasts
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OSTEOCLASTS?Large (up to 100 ?m)
?Multi-nucleated (up to 50 nuclei in the actual cell)
?Arise by the fusion of monocytes
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?Resorption bays/Howship's lacunae?Stimulated by parathormone
?Inhibited by calcitonin
FORMATION OF BONE: INTRAMEMBRANOUS
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?Osteoprogenitor cells
?Osteoblasts - deposit osteoid
?Woven network - no lamellae
?Osteoid calcifies
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?Primitive trabecular bone?Primitive compact bone
?Subsequent reorganisation
INTRAMEMBRANOUS OSSIFICATION
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INTRAMEMBRANOUS OSSIFICATION
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ENDOCHONDRAL OSSIFICATION
?Cartilage bone model
?Calcification of intercellular substance (ALP)
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?Periosteal bud invasionENDOCHONDRAL OSSIFICATION
?Osteoprogenitor cells - enter hypertrophied and partial
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calcified cartilage
?Mature into osteoblasts
?Deposition of new bone on calcified cartilage
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ENDOCHONDRAL OSSIFICATION
ENDOCHONDRAL OSSIFICATION
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EPIPHYSEAL PLATE
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EPIPHYSEAL PLATE1. Resting zone
2. Proliferation zone
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3. Hypertrophic zone
4. Calcification zone
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5. Ossification zoneGROWTH OF BONE
Bone formation and bone resorption go hand in
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hand during the growth of bone.
REORGANISATION AND RESTORATION
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?During growth period and continues
?Changes of tensile and compressive forces.
?Wear and tear occurring in bone
?Osteoclasts and osteoblasts
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?Forms new Haversian system within the matrix ofcompact bone.
?Older Haversian systems - interstitial lamellae
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?Capillaries and nerves sprout inOSTEOPOROSIS
WHAT IS COMPACT BONE?
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a. Dense bone
b. Woven bone
c. Immature bone
d. Spongy bone
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WHAT CELL IS INVOLVED IN BONE RESORPTION?
a. Osteoclast
b. Osteon
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c. Osteocyted. Osteoid
WHAT TYPE OF BASIC TISSUE TYPE IS
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BONE?a. Epithelium
b. Connective tissue
c. Muscle
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d. BoneWHAT IS WOVEN BONE?
a. Cancellous bone
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b. Dense bonec. Immature bone
d. Spongy bone
WHAT ARE THE SPICULES ON SPONGY
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BONE CALLED?a. Canaliculi
b. Sharpey's fibers
c. Trabeculae
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d. LacunaWHAT IS BONE FORMATION CALLED WHEN
THE BONE IS FORMED DIRECTLY, WITHOUT
USING A CARTILAGE TEMPLATE?
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a. Intraosseous
b. Intramembranous
c. Endochondral
d. Endosteum
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WHAT FORMS THE EPIPHYSEAL GROWTH
PLATE?
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a. Fibrocartilageb. Hyaline cartilage
c. Compact bone
d. Spongy bone
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