1. BONE SSN Histology

2. The Basics Specialized connective tissue: –mineralized matrix (hydroxyapatite) Type I Collagen; Proteoglycans; Non- collagenous Glycoproteins Functions: –Mechanical support –Calcium homeostasis –Encloses bone marrow

3. Cells Osteoblasts = osteocyte progenitors; secrete ground substance for osteoid Lab 5, Slide 30

4. Cells Osteocytes = mature, non-dividing bone cells; enclosed in calcified bone matrix

5. Osteoclasts = remodeling/ resorption by using lysosomal enzymes

6. Cells Osteoclasts: Limited bone resorption Active bone resorption

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

8. Mature vs. Immature Bone Immature Bone (Woven) Nonlamellar Found in fetus or following a fracture

9. 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)

10. Endochondral vs. Intramembranous Endochondral Intramembranous

11. Endochondral Ossification

12. Zone of Proliferation Zone of Reserve Cartilage

13. Zone of Hypertrophy Zone of Proliferation Endochondral Ossification

14. Zone of Calcification Zone of Resorption Endochondral Ossification

15. Ground Bone Preparation of Bone Samples

16. Ground Bone Preparation of Bone Samples

17. Decalcified Bone Preparation of Bone Samples

18. 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

19. Question 1... Panel APanel B

20. Questions 2 & 3... Figure AFigure B

21. Questions 4 & 5... Panel A Panel B

22. Question 6...