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

Osteoclasts = remodeling/ resorption by using lysosomal enzymes

Cells Osteoclasts: Limited bone resorption Active bone resorption

Mature vs. Immature Bone Mature (Lamellar) Compact (Cortical)Spongy (Cancellous) w/ Haversian systemsw/ 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

Zone of Hypertrophy Zone of Proliferation Endochondral Ossification

Zone of Calcification Zone of Resorption Endochondral Ossification

Ground Bone Preparation of Bone Samples

Ground Bone Preparation of Bone Samples

Decalcified Bone Preparation of Bone Samples

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: Real Players Have Cool Rides

Question 1... Panel APanel B

Questions 2 & 3... Figure AFigure B

Questions 4 & 5... Panel A Panel B

Question 6...