Histology - Compact Bone
Microscopic structure of bone (along the diaphysis)
The periosteum.
- Internal to it, lie columns of compact bone, called osteons.
- Centrally, within the osteons, run the Haversian (aka central) canals, in parallel.
- Volkman's (aka perforating) canals run in perpendicular to them.
- These canal systems form channels for the neurovasculature.
- The osteon comprises concentric rings of lamellae – the bone connective tissue.
- Osteocytes are a mature form of osteoblast (the bone-producing cells) within the bony matrix; they are concentrically arranged in between the circles of lamellae. They lie within lacunae (cavities) that interconnect via canaliculi (which are spindly, like spider legs) and through which the osteocytic cytoplasmic cell processes connect for the transportation of nutrients and waste.
- The outer layer forms the cement line.
- Interstitial lamella lie in between the osteons, which comprises remnants of partially resorbed osteons.
- Sharpey's fibers are collagenous fibers that anchor the periosteum to the outer lamellae.
Endosteum
- Lies internal to the compact bone. It comprises:
- An inner-circumferential lamellae
- Osteoprogenitor cells
- Spongy bone lies internal to the endosteum and comprises a network of lamellae that do NOT form the Haversian channels and osteons found in compact bone.
For reference, show that hematopoetic marrow fills the marrow cavity, which is left when the spongy bone is reabsorbed during bone development (learned elsewhere).
Histological Slides
Compact bone
- Osteon
- Haversian (aka central) canal
- Interstitial lamella
- Osteocyte within a lacuna
Osteon (at higher resolution)
- Concentric pattern of lamellae (the bony layer).
- External to this lamella, show a lacuna.
- Canaliculi radiate from it
- Haversian canal
- Edge of a Volkman's canal, which perforates it perpendicularly.