Download MBBS Anatomy PPT 32 Histology Of Bone Notes

LEARNING OBJECTIVES

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Histological Organisation of Bone
Bone Cells and Matrix
Formation of Bone

Intramembranous Ossification

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Endochondral Ossification

Reorganisation and Restoration of Bone

STRUCTURE OF LONG BONE

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BASED ON BONE MATURITY

Lamellar bone

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WOVEN BONE

LAMELLAR 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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Ground section - unstained

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TRABECULAR BONE

No Haversian systems

PAGET'S DISEASE

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Woven bone and Lamellar bone in disorganised manner

BONE 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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(Haematopoietic cells)

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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 invasion

ENDOCHONDRAL 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 PLATE

1. Resting zone

2. Proliferation zone

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3. Hypertrophic zone

4. Calcification zone

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5. Ossification zone

GROWTH 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 of

compact bone.

?Older Haversian systems - interstitial lamellae

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?Capillaries and nerves sprout in

OSTEOPOROSIS

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. Osteocyte
d. 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. Bone

WHAT IS WOVEN BONE?

a. Cancellous bone

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b. Dense bone
c. 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. Lacuna

WHAT 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. Fibrocartilage
b. Hyaline cartilage
c. Compact bone
d. Spongy bone