Histology - Specialized Connective Tissues (BONE)

Histology - Specialized Connective Tissues (BONE)

1. SPECIALIZED CONNECTED TISSUE: BONE Clara Corpuz Emsi Cipriano Jacob Dela Cruz

2. BONE TISSUE Bone Matrix: consists of cells, fibers and ECM made up of type 1 collagen Highly vascular + Mineral deposition: Bone → Calcified Bear more wt Withstand stress Provide attachment sites for muscles and organs Hematopoiesis Storage of Ca+2 and phosphate

3. BONE MATRIX Bone Matrix: consists of cells, fibers and ECM made up of type 1 collagen Organic components: sulfated glycosalmiglycans and hyaluronic acid → larger proteoglycan aggregrates Mineralization: Glycoproteins osteocalcin and osteopontin bind to calcium Sialoprotein binds osteoblasts to ecm through integrins of plasma membrane Inorganic components : Calcium + phosphate = hydroxyapatite crystals + collagen fibers = bone hardness durability strength

4. BONE CELLS Osteoprogenitor cells: undifferentiated, pleuropotential stem cells Osteoblasts: @ surface of the bone that synthesize, secrete bony matrix; active Osteocytes: mature form of osteoblasts; maintain the structural integrity of the matrix Osteoclasts: resorb bone during remodeling

5. PROCESS OF BONE FORMATION Endochondrial Ossification Intramembranous Ossification

6. Endochondral Ossification Hyaline Cartilage → Interstital and Appositional Growth → Chondrocytes divide and enlarge → Cartilage Calcify → diffusion of nutrients ↓ chondrocytes die fragmented → calcified matrix → Periosteum → osteoprogenitor cells (arise from endosteum ) and bv invades → Osteoblasts Mesenchyme + Osteoblasts + Bv = Ossification center Long bones: primary ossification center in diaphysis → secondary in epiphysis → Osteoid Matrix → bone (x epiphyseal plate region)

7. INTRAMEMBRANOUS OSSIFICATION No cartilage forms the mandible, clavicles, and flat bones of the body Mesenchyme → Osteoblasts → osteoid → calcified → osteocytes w/ lacunae

8. Two Kinds of Bone Compact bone Spongy Bone

9. Spongy Bone Also called cancellous or trabecular bone No formal osteons Trabeculae Forms most of the structure of short, flat, and irregular bones, and the epiphyses of long bones.

10. Spongy bone (Trabeculae) Latticework of thin plates of bone oriented along lines of stress Contains red bone marrow ( hemopoiesis ) Found in ends of long bones and inside flat bones such as the hipbones, sternum, sides of skull, and ribs.

11. Red bone marrow in spongy bone

12. Slide Observed under LPO

13. Two Kinds of Bone Compact Bone Spongy Bone

14. Histology of Bone Tissue

15. Compact Bone The structural unit of compact bone is the osteon or Haversian system . Each osteon is an elongated cylinder running parallel to the long axis of the bone . It actually contains canals and passageways that provide access for nerves, blood vessels, and lymphatic ducts. Each columns is made up of concentric rings or lamellae along the calcified matrix.

16. Concentric layers or rings along the calcified matrix. Tiny cavities inside the lamellae. This is the space where the osteocyte are found. It is the central canal that is surrounded by concentric lamellae. Tiny hair-like channels that are branching. Compact Bone

17. Connects two Haversian canals. Canals lie at right angles to long axis of bone. Connect the vascular supply of the periosteum to those of the central canal and medullary cavity. Volkmann’s canal

18. Histology of Bone Tissue

19. Canaliculi Haversian canal Circumferencial lamellae Osteocyte surrounded by lacuna Interstitial lamellae Haversian system/ Osteon OIO Decalcified human bone

20. REFERENCES Difiores ’ Atlas of Histology 11 th Ed. http:// www.freezingblue.com/iphone/flashcards/printPreview.cgi?cardsetID=266224 http://www.wisegeekhealth.com/what-is-spongy-bone.htm http://www.gla.ac.uk/t4/~ fbls/files/fab/tutorial/generic/bone2.html