Bone Anatomy and Histology by Luis Filgueira · Bone Anatomy and Histology by Luis Filgueira What...
Transcript of Bone Anatomy and Histology by Luis Filgueira · Bone Anatomy and Histology by Luis Filgueira What...
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Bone
Anatomy and Histologyby
Luis Filgueira
What is bone?
Connective Tissue
Cells <> Extracellular Matrix
Bone forming cells <> Bone resorbing cells
Bone Tissue <> Bone Marrow
Organic matrix <> Inorganic matrix
Collagen <>Calcium apatite
Function(s)?
What is cartilage?
Connective Tissue
Cells <> Extracellular Matrix
Bone <> Cartilage
Calcified Matrix
Blood vessels/nerves
Repair/Remodelling
YES
YES
YES
NO
NO
NO
Cells = Chondrocytes
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= live tissue with high turnover
= specialised connective tissue
Principles of connective tissue
Cells <> Extracellular matrix
Types of connective tissue
1. Embryonic connective tissue
2. Connective tissue proper
3. Fat tissue
4. Cartilage
5. Bone
Bone
Cells <> Extracellular matrix
Principles of connective tissue
Cells1. Connective tissue proper <> Fibroblasts/fibrocytes
2. Fat tissue <> Adipocytes
3. Cartilage <> Chondrocytes
4. Bone <> Osteoblasts/osteocytes
Extracellular matrix
produced and secreted by the cells1. Ground substance
2. Fibres
3. Minerals
4. Water
Bone remodelling
Continuous adaptation of bone depending on
Age
Mechanics
Hormones
Nutrition
Formation of new bone tissue
Resorption of old bone tissue
Osteoblasts Osteoclasts
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Addition/growth of bone = appositional growth
Osteoblasts
Arrange in a row on the surface of bone
Produce new matrix = osteoid
Enclose themselves inside the matrix
Osteoblasts become osteocytes
New matrix is calcified
Osteoprogenitor cells are recruited onto the bone surface
Teitelbaum and Ross, Nature Reviews Genetics 2003, 4, 638
Differentiation and function of osteoclasts
is under tight control of osteoblasts
Osteoclasts
Haematopoietic Stem Cell
Blood Monocyte
MacrophageOsteoclast Dendritic cell
Erythrocyte
Lymphocyte
Granulocyte
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What happens if there is no RANK?
Osteoblasts/osteocytes
Stromal Stem Cell
Osteoprogenitor Cell
Osteoblast
Osteocyte
Fat Cell/Lipocyte
Muscle Cell
Fibroblast
Chondrocyte
3 principles of skeleton formation
Direct formation of bone tissue
=
intramembranous ossification
Formation of cartilage tissue
=
cartilage skeleton
First formation of cartilage model
and secondary replacement of
cartilage by bone tissue
=
enchondral ossification
Embryonic bone formation
Bone remodelling
Bone repair
Only during embryology
Embryonic bone formation
Bone growth
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Mesenchymal cells
of head and
neural crest
3 principles of skeleton formation
intramembranous ossification
most of skull
cartilage skeleton
Nose
Ears
Larynx
Articular cartilage
enchondral ossification
Axial skeleton
Skeleton of limbs
Primary bone tissue <> Intramembraneous ossification
Embryonic formation of most bones of the skull
Bone repair
Differentiation of stem cells to
osteoblasts
Production of
extracellullar
matrix
Cells enclose
themselves into
the matrix
Osteoblasts become osteocytes
Matrix is calcified
Osteocytes = functional syncytium
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First formation of cartilage model
and secondary replacement of
cartilage by bone tissue
=
enchondral ossification
Alcian blue / Alazarin red
Enchondral ossification
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Osteoblasts/osteocytes
Stromal Stem Cell
Osteoprogenitor Cell
Osteoblast
Osteocyte
Fat Cell/Lipocyte
Muscle Cell
Fibroblast
ChondrocyteSOX9
RUNX2
Cbfa1/Runx2
Deficiency
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Cbfa1/Runx2
RUNX2 mutation
Holoprosencephaly and cleidocranial
dysplasia in a patient due to two positioneffect
mutations
Osteoblasts/osteocytes
Stromal Stem Cell
Osteoprogenitor Cell
Osteoblast
Osteocyte
Fat Cell/Lipocyte
Muscle Cell
Fibroblast
ChondrocyteSOX9
RUNX2
PPAR
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Osteoblasts/osteocytes
Stromal Stem Cell
Osteoprogenitor Cell
Osteoblast
Osteocyte
Fat Cell/Lipocyte
Muscle Cell
Fibroblast
ChondrocyteSOX9
RUNX2
PPAR
Wnt
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Why enchondral ossification?
1. Bone template of cartilage
2. Longitudinal growth
3. Articular cartilage
Most bones undergo
enchondral ossification
Enchondral ossification
Epiphyseal growth plate
<>
Longitudinal bone growth