Compact bone. Coloured scanning electron micrograph (SEM) of a transverse section of compact bone. The Haversian canal (circular hole, centre) contains blood vessels, lymphatics and nerves. Haversian canals are interconnecting neurovascular channels which run parallel to the long axes of long bones. Concentric bony layers, the lamellae, enclose the Haversian canals. The lamellae are made of compacted collagen fibres and ground substances produced by specialised cells called osteoblasts. During bone formation the osteoblasts become progressively trapped in lacunae (small dark pits). Magnification: x640 at 5x7cm size. x1680 at 8x6inch size.