2. By the end of this session the student is
• Define bone tissue.
• Identify the different components of bone tissue.
• Identify the different types of bone tissue and their
• Identify the osteon.
• Bone is a specialized type of connective tissue for
• It is a mineralized tissue that gives mechanical and
metabolic functions to the skeleton.
1. Support fleshy structures.
2. Protection of vital organs (brain, heart & lungs).
3. Harbors bone marrow (blood cells formation).
4. Reservoir of calcium.
5. Transform skeletal muscle contractions into body
5. Components of bone tissue:
• Intercellular calcified material.
6. Bone cells: Osteoblasts
• Bone forming cells.
• Found at surfaces of bone tissue.
• Synthesize the organic bone matrix.
• Active cells are cuboidal to colomnar in shape while flat ones
• Transformed into osteocytes.
7. Bone cells: Osteocytes
• Flat almond shaped.
• Situated in lacunae, one cell per lacuna.
• Communicate with each other through gap junctions.
• Actively maintain bone matrix.
• Osteocyte death is followed by matrix resorption.
8. Bone cells: Osteoclasts
• Large branched multinucleated motile cells.
• For resorption and remodeling of bone tissue.
• Found in Howships lacunae.
• Active osteoclasts have ruffled border facing bone matrix.
• Control is by cytokines and hormones (calcitonin).
11. Periosteum and endosteum:
• External and internal
coverings of bone.
• Composed of bone forming
cells and connective tissue.
- Nutrition of osseus tissue.
- Provision of continuous
supply of osteoblasts
12. Periosteum & endosteum:
• Outer layer of collagen fibers and fibroblasts.
• Inner layer of fibroblast like osteo-proginator cells.
• periosteal collagen fibers (perforating or Sharpeyfibers)
penetrate the bone matrix, binding the periosteum to
• Lines all internal bone cavities by a single layer of flat
14. Type of Bone Histological Features Major Locations Synonyms
Woven bone, newly
Irregular and random
of cells and collagen;
hard callus of bone
Parallel bundles of
collagen in thin
layers (lamellae), with
spaced cells between;
All normal regions of
of all lamellar bone
Parallel lamellae or
packed osteons, with
Thick, outer region
periosteum) of bones
~20% of all lamellar
trabeculae covered by
Inner region of
to marrow cavities
15. Osteon or haversian system:
• Organization related to lamellar bone.
• Consists of lamellae organized concentrically around small
central canals containing blood vessels and nerves.
16. Osteon or haversian system:
• Within each osteon osteocytic lacunae occur between
the lamellae, with canaliculi radiating through the
lamellae, which allow all cells to communicate with the