Compact bone, light micrograph. Bone is a dense matrix of calcium minerals and collagen, formed by cells called osteoblasts. Compact bone consists of concentric layers of collagen-containing matrix (lamellae), around Haversian canals (several seen here in cross-section), which contain blood and lymph vessels, and nerves. These canals run the length of the bone. The lamellae and canals together form a Haversian system, or osteon. This is a sample from a cow.