Compact bone. Coloured scanning electron micrograph (SEM) of Haversian canals in compact bone. Bundles of Haversian canals form the core of compact bone. Each canal is surrounded by a series of rings of bone (lamellae), known as a Haversian system, formerly housed blood vessels and nerves. The smaller elliptical pits (called lacunae) are the locations of the osteocytes, the bone-forming cells. Throughout growth and adult life, compact bone is constantly being reabsorbed and refashioned. Magnification: x215 at 6x7cm size.