2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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Transcript of 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
http://slidepdf.com/reader/full/2nd-lecture-on-histology-of-bone-by-dr-mudassar-ali-roomi 1/23
HISTOLOGY OF BONE
BY
DR. MUDASSAR ALI ROOMI (MBBS, M. Phil.)
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
http://slidepdf.com/reader/full/2nd-lecture-on-histology-of-bone-by-dr-mudassar-ali-roomi 2/23
Bone matrix
• It is the extracellular substance in the bone.
• Composed of inorganic (mineral) and organic
components
•
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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Bone matrix
INORGANIC (MINERAL)
COMPONENT:• 65 % of the dry weight of the
bone.
• Responsible for hardness of the bone.
• Ca and PO4 are present in theform of hydroxyapatitecrystals.
• Bone – inorganic component =bone looses its rigidity andbecomes as flexible as a
tendon
ORGANIC COMPONENT:
• 35 % of the dry weight of bone.
• Consists of collagen fibers (95% of the organiccomponent)and amorphous
ground substance.• Too much collagen gives
acidophilia to the bone tissue.
• The ground substance:chondroitin SO4 and keratanSO4.
• Bone – organic component =white, brittle and fragile massof bone which breaks easily.
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
http://slidepdf.com/reader/full/2nd-lecture-on-histology-of-bone-by-dr-mudassar-ali-roomi 4/23
TYPES OF BONE
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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LOCATION FO COMPACT AND SPONGY BONE
• Epiphysis are composed
of spongy bone and
covered by a thin layer
of compact bone
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
http://slidepdf.com/reader/full/2nd-lecture-on-histology-of-bone-by-dr-mudassar-ali-roomi 6/23
LOCATION FO COMPACT AND SPONGY BONE
• The flat bones of skull
are composed of two
layers (tables) of
compact boneseparated by a thin
layer of spongy bone.
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
http://slidepdf.com/reader/full/2nd-lecture-on-histology-of-bone-by-dr-mudassar-ali-roomi 7/23
LOCATION OF COMPACT AND SPONGY BONE
• Shaft (diaphysis) of
long bones consists
almost entirely of
compact bone.• Only a thin layer of
spongy bone lines the
inner surface of the
shaft immediatelysurrounding the
Medullary cavity.
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
http://slidepdf.com/reader/full/2nd-lecture-on-histology-of-bone-by-dr-mudassar-ali-roomi 8/23
COMPARISON
COMPACT BONE
• Location: In the shaft of long
bones and also in the skull
bones and in the epiphysis.
• Lamellae: arranged to form
Haversian system (osteon).
• Bone marrow: red before
puberty and yellow after
puberty.
• Nature: hard and ivory like
SPONGY BONE(cancellous bone)
• In the epiphysis of long
bones
• Arranged in the form of a
meshwork of bone trabeculae. No
Haversian system
• Red bone marrow.
• spongy
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
http://slidepdf.com/reader/full/2nd-lecture-on-histology-of-bone-by-dr-mudassar-ali-roomi 9/23
COMPACT BONE
We will discuss it under the following heads:
• It has got a lamellar structure (4 types)
•
Periosteum: outer covering of bone.• Endosteum: inner covering of bone which
lines the medullary cavity.
•
Canals (2 types): Haversian and volkmann’s • Bone cells
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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Periosteum
• it is the outer most covering of bone.
• It is absent at the articularsurfaces.
• It consists of two layers.
• outer layer of irregularlyarranged dense collagen fibers
• inner cellular layer which lodgesinactive (resting) fibroblastwhich appear as flattened cells.
•Periosteum is pain sensitive
• Sharpy’s fibers: some of thecollagen fibers from theperiosteum penetrate the bonematrix obliquely and bind theperiosteum to bone.
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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Lamellae of compact bone
1. Periosteal (outercircumferential)lamellae
2. Haversian (concentric)lamellae
3. Interstitial lamellae
4. Inner circumferential
lamellae• Each lamella is 3-7 um
thick.
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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HAVERSIAN SYSTEM (OSTEON)
• It is the structural unit of the bone tissue.
• It is long cylinder that runapproximately parallel tothe long axis of bone.
• Surrounded by cementsubstance.
• It is composed of :
1. 5-20 concentric lamellae
2. Osteocytes in the lacunae3. Lacunae are located b/w
the successive lamellae.
4. Haversian canal (whichcontains blood vessels,
nerves, and loose C.T.)
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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Compact bone (t.s)
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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Compact bone (L.S)
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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OSTEONS (wow!)
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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Canaliculi between Osteocytes
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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Compact bone (t.s)
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
http://slidepdf.com/reader/full/2nd-lecture-on-histology-of-bone-by-dr-mudassar-ali-roomi 20/23
Compact bone
Identification points:
1. Characteristic lamellae
2. Haversian canal
3. Volkmann’s canal
4. Typical bone cells
5. Haversian system
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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Spongy bone
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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Spongy bone
It is idntified by:
1. Trabeculae of the bone
matrix
2. Haemopoitic (bone
marrow) tissue
3. Few Haversian system
8/2/2019 2nd Lecture on Histology of Bone by Dr Mudassar Ali Roomi
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COMPARISON BETWEEN
CARTILAGE
• Fibers: Type I and Type II
collagen fibers.
• Vascularity: avascuar• Nerves : absent
• Repair: low
• Communications between
cells: absent
• Hydration: high (75%)
• Mineralization: no
BONE
• Type I collagen fibers.
• Highly vascular.
• Present.
• High
• Gap junctions b/w
osteocytes.
• Low (7%)
• Ca, PO4