Endochondral ossification

The epiphysis is the terminal enlargement of a long bone. Its periphery is formed of a thin layer of compact bone, while the interior is spongy bone and red marrow. The proximal epiphysis of the femur has been modified to form a head and neck.

Growth in length occurs from a region of hyaline cartilage, the epiphyseal plate. The locations of two epiphyseal plates (green arrows) are still present in the left images. After chondrocyte proliferation stops, further growth in length ceases and only an epiphyseal line remains to indicate the original location of the plate.

The metaphysis is the funnel-shaped segment of bone interposed between the diaphysis and the epiphyseal plate (if the bone is still growing in length) or the epiphyseal line and adjacent epiphysis (if growth has ceased).

The diaphysis of the bone is composed of compact bone and is filled with yellow marrow in the adult.

Compact bone covers the periphery of the entire bone and forms the thick bone comprising the diaphysis of a long bone.

Spongy bone is found in the interior of the bone, filling the epiphyses and lining the compact bone in the diaphysis. Red marrow fills the spaces of spongy bone in the epiphyses.

Spongy bone is found in the interior of the bone, filling the epiphyses and lining the compact bone in the diaphysis. Red marrow fills the spaces of spongy bone in the epiphyses.