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BONE . SSN Histology . The Basics. Specialized connective tissue: mineralized matrix (hydroxyapatite) Type I Collagen; Proteoglycans; Non-collagenous Glycoproteins Functions: Mechanical support Calcium homeostasis Encloses bone marrow. Cells.
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BONE SSN Histology
The Basics • Specialized connective tissue: • mineralized matrix (hydroxyapatite) • Type I Collagen; Proteoglycans; Non-collagenous Glycoproteins • Functions: • Mechanical support • Calcium homeostasis • Encloses bone marrow
Cells Osteoblasts = osteocyte progenitors; secrete ground substance for osteoid Lab 5, Slide 30
Cells Osteocytes = mature, non-dividing bone cells; enclosed in calcified bone matrix
Cells Osteoclasts = remodeling/ resorption by using lysosomal enzymes
Cells Osteoclasts: Active bone resorption Limited bone resorption
Mature vs. Immature Bone Mature (Lamellar) Compact (Cortical) Spongy (Cancellous) • w/ Haversian systems • w/ trabecular appearance
Mature vs. Immature Bone Immature Bone (Woven) • Nonlamellar • Found in fetus or following a fracture
Appositional vs. Interstitial • Appositional = bone growth on pre-existing bone surface • Note that bone tissue only undergoes appositional • Interstitial = bone growth via new cartilage formation within pre-existing cartilage mass • Note that it is cartilage that undergoes interstitial • Long Bone Growth: • WIDTH --> Appositional (bone) • LENGTH --> Interstitial (cartilage)
Endochondral vs. Intramembranous Endochondral Intramembranous
Endochondral Ossification Zone of Proliferation Zone of Reserve Cartilage
Endochondral Ossification Zone of Hypertrophy Zone of Proliferation
Endochondral Ossification Zone of Calcification Zone of Resorption
Preparation of Bone Samples Ground Bone
Preparation of Bone Samples Ground Bone
Preparation of Bone Samples Decalcified Bone
Final Thoughts…. • Let staining properties guide you • Note cellularity; compare size, color, shape, relative quantity of cells • Haversian = central to osteon • Volkmann’s = perpendicular • Think of bone as specialized connective tissue; always in a dynamic state • Long bones = endochondral • Parietal bones = intramembranous • Mnemonic for Endochondral: RealPlayersHave CoolRides
Question 1. . . Panel A Panel B
Questions 2 & 3. . . Figure A Figure B
Questions 4 & 5. .. Panel B Panel A