Osteogenesis

Numerous factors are involved in the process of bone generation. An imbalance in this process can lead to serious diseases such as osteogenesis imperfecta (OI), a genetic disease characterized by extremely brittle bones. There are 4 subtypes of OI, depending on the genetic mutation:

  • Osteogenesis imperfecta type I

  • Osteogenesis imperfecta type II

  • Osteogenesis imperfecta type III
  • Osteogenesis imperfecta type IV

Osteogenesis is the normal biological process of bone formation. It begins in the eighth week of embryonic development, during which the ability to repair possible future fractures occurs. It must be taken into account that the bones of the human skeleton derive from three embryonic structures: the mesoderm, the somites and the neural crest.

Mesoderm

The mesoderm is one of the three cell layers from which the entire embryo develops. In the beginning, there are three layers of mesoderm cells: ectoderm, endoderm and mesoderm (between the ectoderm and endoderm). The mesoderm gives rise to the bones of the extremities.

Somites

Somites are transient embryonic structures fundamental for the development of the segmented structures that are characteristic of vertebrates. Moreover, bones that are part of the central axis of the body or axial skeleton derive from somites, such as the hyoid bone, the ribs, the spine, the sternum, the skull and auditory bones.

Neural Crest

Are transitory cell formations, typical of the early stages of development. Its main characteristic is the pluripotency of its cells. In other words, the cells of the neural crest allow the appearance any type of osseous structure of the body. For example, craniofacial bones and cartilages

Osteogenesis is also called ossification and consists of the transformation of preexisting tissue into bone tissue. To carry out this transformation there are two mechanisms:

-Endochondral ossification:

It is a more complex process characterized by the formation of bone from cartilaginous tissue during embryonic development.

-Intramembranous ossification:

Through this process, the flat bones of the skull are formed, where ossification occurs inside a membrane of connective tissue. Some cells from this membrane will become osteoblasts, the cells in charge of secreting the bone matrix. While others become part of the small blood vessels that supply the bones.

If the process of osteogenesis is faulty, the result is osteogenesis imperfecta. Osteogenesis imperfecta (OI) is also known as brittle bone disease, a genetic disease characterized by excessive fragility of the bones.

People who suffer from it suffer constant fractures in addition to other symptoms such as blue sclera. The physiopathology comes as a result of mutations in the genes Cola1A1 and Cola1A2, ending up with an altered structure for collagen type 1, an essential component of the bone matrix. The lack of normal collagen type 1 is responsible for the excessive fragility of the affected bones.

Osteogenesis imperfecta is a disease considered rare since a small number of people suffer from this affliction. It has a very variable prognosis because there are different types of severity. In addition, the evolution of the disease itself also varies a lot between patients and depends on a large number of factors.

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