The central canal and lacuna are both structures found within bone tissue, but they serve different purposes and are located in distinct areas.
The central canal, also known as the Haversian canal, is situated in the center of an osteon, which is the fundamental unit of compact bone. This canal contains blood vessels, nerves, and lymphatics, providing nutrients and signaling to the bone tissue. The fluid found in the central canal is primarily blood and interstitial fluid.
On the other hand, a lacuna is a small cavity located between the lamellae in the bone matrix. Each lacuna houses an osteocyte, which is a mature bone cell. The material found in the lacuna is primarily the osteocyte and its surrounding fluid. The osteocyte communicates with other bone cells through tiny channels called canaliculi, which connect the lacunae to both the central canal and to each other.
In summary, the central canal is centrally located within an osteon and mainly contains blood vessels and nerves, while lacunae are tiny spaces between the bone layers that contain osteocytes.