There are two processes of development of the bone from fertilisation to adulthood and are intramembranous and endochondral ossification. Intramembranous ossification takes place throughout the flat bone of the skull. It is also responsible for developing jaws, clavicles and collar bones. A development starts after mesenchymal cells in the embryonic skeleton collect together and distinguish into osteoblasts, developing an ossification centre. Osteoblasts start to secrete osteoid and are calcified in a couple of days where mineral salts are placed on it so trapping the osteoblasts inside. After trapped, osteocytes develop into osteocytes. A formation of woven bone and periosteum take places. A bone collar of compact bone forms and red marrow
