What is intramembranous ossification?

Intramembranous ossification is a process in the human body by which the long bones, clavicles, flat bones, and the skull, are formed during the fetal development and also happens when there is a fracture of a bone.

In essence, this process determines the specification of mesenchymal stem cells into what will later on be known as osteoblasts and then osteocytes. Basically, what happens is that the mesenchymal cells, at a stimulus, begin to replicate and form what is known as a nidus. As these cells replicate, grow and specialize, they start to form the basic unit of bones, which are known as osteocytes. In order for this to happen, the mesenchymal cells will undergo several changes, and adaptations, to elongate, grow and then form the tissue. They will also become able to capture minerals, such as calcium, in order to finish their formation.