Cartilage, light micrograph. Early ossification centre in foetal and neonatal life showing the cartilaginous stage of bone formation where a future long bone is chiefly hyaline cartilage comprising chondrocytes and cartilage matrix stained pink and deep blue. Chondrocytes and matrix will be replaced with new bone tissue via the invasion of bone-forming cells osteoprogenitor/osteoblasts. These cells are introduced by capillaries in the region at bottom. Replacement of the initial cartilaginous model with new bone is called endochondral ossification and is completed in postnatal life. Epoxy resin section, Toluidine blue stain. Magnification: x580 when width printed at 10cm.