Bone. Polarized light micrograph (PLM) of a sectioned femur (thigh) bone. This compact tissue comprises the walls of bone shafts. Haversian canals (small circles) contain blood, lymph vessels and nerves. Each canal and its associated lamellae (pink/yellow) forms a Haversian system, or osteon. Many Haversian systems are arranged in columns running down the long axis of the bone. Osteocytes (not seen), the cells that maintain the bony matrix, are housed in spaces (lacunae) within the osteons. The outermost cortical layer is arranged in concentric lamellae (blue, lower frame) that extend around the bone shaft. Magnification: x13 at 35mm size.