Bone formation. Light micrograph showing bone growth occurring along an epiphyseal growth plate. This plate allows long bones to grow whilst also remaining strong. At the plate, a glycoprotein matrix (dark blue band, bottom right corner to upper centre) separates columns of dividing chondrocytes (cartilage cells, light blue). During bone formation the matrix hardens and its cavities are invaded by osteogenic cells, which differentiate into osteoblasts. These group on the cartilage matrix (resulting in the white and pink tissue, lower left) and produce new bone (solid pink). Trichrome stained. Magnification: x20 at 35mm size.