Bone tissue. Light micrograph of a section through adult compact bone tissue, showing the many osteons in cross-section. Osteons, or Haversian systems, are branching cylinders of concentric layers of bone matrix and their embedded cells (osteocytes), with a central canal for blood vessels. These appear empty in this specimen but when such canals link osteons together they are called Volkmann's canals. The bone matrix between osteons is older and represents in part the remnants of previous osteons that have been replaced with the development of new osteons. Bone is a living tissue that is constantly being resorbed and replaced. Magnification: x5 when printed 10 centimetres wide.