The Joy of Ossification
Ossification and osteogenesis are synonyms meaning the process of bone formation. In embryos this process leads to the formation of the bony skeleton. As a person grows, another form of ossification known as bone growth goes on until early adulthood as the body continues to increase in size. Bones are capable of growing in thickness throughout life. Intramembranous ossification takes place within the womb and is the process by which flat bones such as some of the bones of the skull and the collarbones are created from connective tissue. It also is the process for injured bones to heal and occurs when bones are broken or damaged in order to reconstruct the bone. Another process occurring during embryonic development is endochondral ossification, a process in which bones are produced from cartilage. Endochondral ossification occurs in the development of long bones such as the arms and legs. In intramembranous ossification, there is no cartilage present, and the bones develop from other connective tissues instead. Both of these types begin as mesenchyme. During intramembranous ossification, fibrous connective tissue membranes are formed from fibrous membrane called mesenchyme. Cartilage is not present in this type of ossification process. There are four main stages of intramembranous ossification. First, an ossification center appears in the fibrous connective tissue membrane. When selected, centrally located mesenchymal cells cluster and differentiate into osteoblasts, an ossification center is formed. Mesenchymal cells, collagen fibers, an ossification center, osteoids, and osteoblasts make the scene in the first stage of intramembranous ossification.
The second step is when bone matrix, also known as an osteoid, is secreted within the fibrous membranes and calcifies. This occurs because osteoblasts begin to secrete this osteoid which is then mineralized (calcified) within a few days which causes the trapped...
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