Growing Bone

Zooming in closer on the growth plate it is possible to see the stages of bone growth. The blue stained cartilage cells are lined up in columns. At the top (epiphyseal side) of the column the cells divide quickly as they undergo mitosis. This increases the thickness of the epiphyseal plate. As the cells divide they push epiphysis away from the diaphysis. This lengthens the long bone. Below the rapidly growing cells are older cells that have enlarged. The area surrounding these cells begins to calcify. The calcified matrix results in the cartilage cells dying. Just below the blue band of cells the dead cartilage cells begin to deteriorate. At the bottom pink area ossification occurs as osteoblasts deposit bone material around the remaining parts of the cartilage cells. This forms the bony trabecular.