Lacunocanalicular

Lacunocanalicular refers to the network formed by lacunae and canaliculi in mineralized bone, through which osteocytes reside and communicate. Lacunae are small, ellipsoidal cavities about 10 to 20 micrometers in diameter that house an osteocyte embedded in the bone matrix. Connected to each lacuna are numerous canaliculi, slender channels containing osteocyte processes and pericellular fluid, which extend through the mineralized matrix to contact neighboring lacunae and reach the vascular network.

The lacunocanalicular network is interconnected by gap junctions between osteocyte processes, allowing direct intercellular communication. Typical canalicular diameters are around 0.1 to 0.2 micrometers, and canaliculi can extend tens of micrometers to bridge lacunae and align with Haversian or Volkmann’s canal systems that carry blood vessels and nutrients. The network forms an osteocytic syncytium that coordinates cellular responses across the bone.

Functionally, the lacunocanalicular system supports mechanosensing and transport within bone. Mechanical loading induces fluid flow in canaliculi, generating signals that regulate osteocyte activity and, in turn, influence bone remodeling. Osteocytes also participate in mineral homeostasis and signaling to osteoblasts and osteoclasts through molecules such as sclerostin, RANKL, and OPG, thereby modulating bone formation and resorption.

Clinically, integrity of the lacunocanalicular network tends to decline with aging and certain diseases, contributing to reduced bone quality and increased fragility. Alterations in osteocyte signaling or canalicular connectivity can disrupt remodeling balance and mineral distribution within the skeletal tissue.