Intramembranous Ossification

The intramembranous ossification, which is responsible for the development of flats bones (such as the skull, the mandible and the clavicle etc.) this process, is stem from the embryonic fibrous connective tissues to form solid bones. Whereas, the endochondral ossification is responsible for the development of long bones (such as femur, phalanges, radius and etc.) this stem from a temporary hyaline cartilage model, which is then later replaced by solid bone via osteoblast. Within the intramembranous ossification, the fibrous connective tissue membrane there are mesenchyme cells cluster that are not differentiate, these then differentiate into osteoblasts “bone makers”, forming a ossification centre. This is the primary ossification where bones are first starting to develop usually in the shaft or diaphysis of the bone.

Mineralization of the osteoid then takes place, which is essential for the strengthening and hardening of bones. The osteoblast that is trapped or embedded within the bone matrix “osteoid” then becomes osteocytes. It lies within a lacuna, a small pit, and communicates with its surroundings through tiny channels called canaliculi. These tiny network channels are very essential and are used to get nutrient and minerals that are essential for growth and repair of the bones. This is due to the fact that during our lifetime the bones need to be remodel, repair from fractures and grow. The osteoid calcified into random “needle like” spongy bone called Trabecular which is thin and less dense than lamellar bone. The vascularized mesenchyme condenses on the shaft of the bone and become the periosteum. Primary calcification takes place in the matrix vessels of the mesenchyme cell; the trabecular continues to thicken to develop the woven bone collar, which is mechanically