Canaliculi

Canaliculi (singular canaliculus) are microscopic channels that occur in various tissues and serve as pathways for communication and transport between cells and their surroundings. The term is most often used in reference to bone and liver, where canaliculi form functional networks.

In bone, canaliculi are part of the lacuno-canalicular network that connects osteocyte lacunae through slender cytoplasmic processes extending through the mineralized matrix. These processes are linked by gap junctions, enabling direct intercellular communication. The network allows diffusion of nutrients, signaling molecules, and waste between osteocytes and blood vessels, and it plays a key role in mechanotransduction—cells sensing and responding to mechanical strain.

In the liver, bile canaliculi are small, narrow ducts formed by the apical membranes of adjacent hepatocytes. Tight junctions between hepatocytes create sealed conduits that collect bile secreted by hepatocytes and channel it toward bile ductules in the portal triads. The canaliculi are lined with microvilli to increase surface area and facilitate bile flow. Obstruction or dysfunction of bile canaliculi can contribute to cholestasis and related liver pathology.

Canaliculi also occur in other contexts, such as dentin, where dentinal canaliculi consist of microscopic channels within dentin housing odontoblastic processes and enabling diffusion of nutrients through this tissue.

Overall, canaliculi are small, specialized channels that support cellular communication and transport, with notable examples in bone and liver that underpin nutrient exchange, signaling, and organ function.