The osteon, or Haversian system, is the fundamental functional unit of much compact bone. Osteons, roughly cylindrical structures that are typically several millimeters long and around 0.2 mm in diameter.
Each osteon consists of concentric layers, or lamellae, of compact bone tissue that surround a central canal, the Haversian canal.
The Haversian canal contains the bone’s nerve and blood supplies.
Osteoblasts form the lamellae sequentially, from the most external inward toward the Haversian canal.
Some of the osteoblasts develop into osteocytes, each living within its own small space also known as lacuna.
Osteocytes make contact with the cytoplasmic processes of their counterparts via a network of small canals, or canaliculi. This network facilitates the exchange of nutrients and metabolic waste.
The space between osteons is occupied by interstitial lamellae, which are the remnants of osteons that were partially resorbed during the process of bone remodelling.
Osteons are connected to each other and the periosteum by oblique channels called Volkmann’s canals.
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[...] Lamellar bone has a regular parallel alignment of collagen into sheets (lamellae) and is mechanically strong. It is highly organized in concentric sheets with a much lower proportion of osteocytes to surrounding tissue. Lamellar bone is stronger and filled with many collagen fibers parallel to other fibers in the same layer (osteons). [...]