BoneAlhasien ,Mutaz

MBBS

Introduction Layout

Bone Anatomy &development .

The cartilage histology .

Bone Microanatomy and staining techniques.

Bone Physiology & Pathophysiolgical processes .

Markers of bone formation .

Synovial joints anatomy and Pathology .

Bone Tumors correlates .

FUNCTION OF BONE

COMPOSITION OF BONE

Bone

Inorganic 65% Organic 35%

(Primarily calcium phosphate

which is present in form of

Highly insoluble crystals of Collagen 88-89% Non collagen11-12%

Hydroxy apatite)GlycoproteinProteoglycanSialoproteinsLipids

Collagen fibers provide bone with great tensile strength while Inorganic salts allow bone to withstand compression.

Classification of Bones on the Basis of Shape

Slide 5.4cCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 5.1

6-7Intramembranous Ossification

Growing taller throughout childhood!

SKELETAL CARTILAGE

• Chondrocytes:

• Lacunae:

.

• Extracellular matrix:

• Perichondrium:

Hundreds of Eyes Staring Back at YOU!

Bone Histology

Osteogenic cells:

Normal Bone Microanatomy

Undecalcified transiliac bone biopsies (right) are considered to be representative of all skeletal bone and are suitable for examining, measuring, and analyzing the microscopic features of cortical and cancellous bone. Also, with the appropriate use of absorbable fluorochromeagents, the dynamic changes that occur in bone can be assessed.

Cortical

bone

Cancellous

bone

Anatomic Features of a Normal Transiliac Bone Biopsy

7.5mm

Cortex

Trabeculae

Hematopoietic

and fatty marrow

Normal Bone MicroanatomyDifferential Tissue Stains

A number of differential stains can be used to examine undecalcified tissue. Toluidine Blue stain (left) and Goldner Trichrome stain (right) will be used throughout this presentation, except as otherwise indicated. Each stain has characteristics that favor, or disfavor, its use. Either may be used for histomorphometric analysis.

Unmineralized bone

Mineralized bone

Bone FormationWoven Bone

Under conditions of rapid turnover, e.g., normal growth, fracture healing, or under some pathologic conditions as illustrated, osteoid is deposited in disorganized fashionand is called woven bonein contrast to lamellar bone.

Lamellar bone

Woven bone

Bone physiology

BONE REMODELING

Bone continually renews itself

Enables Ca homeostasis.

Spongy bone replaced every 3-4 years

Compact bone every 10 years

Bone Remodeling

Vitamin D

Nutrition

Physical activity

Age, hormones

PTH, PHRP

IL1, TNF,TGF-β

5-10% bone / year.

Bone RemodelingBone Formation

Unmineralized osteoid

Osteoblasts secrete type I collagen, called osteoid, from their basal surfaces onto the previously resorbed surface. Osteoid forms the organic matrix of bone.

Mineralization of OsteoidThe Mineralization Front

Ten to fifteen days following secretion, osteoid undergoes maturational changes that prepare it for the initial deposition of calcium phosphate crystals.

This occurs along an interface between mineralized and unmineralized bone, called the mineralization front.

Biochemical Effects of Bone RemodelingMarkers of Bone Formation

Osteoblasts secrete collagenous and noncollagenous proteins into circulation, including the C and N-terminal fragments of procollagen, alkaline phosphatase, and osteocalcin. Concentrations of these products in serum and urine serve as “markers” of bone formation and turnover.

6-33

Bone Matrix

SYNOVIAL JOINTS

1) fibroblasts Hyaluronin

Lubricin

2) macrophagesThe SUB-intima is loose CT or fat

One Picture Is Worth Ten Thousand Words– Frederick Barnard, 1927

Thank you