Embryological Sources of Skeletal System:
The skeletal system develop from undifferentiated mesenchymal tissue that differentiate to:
a) osteoblasts (bone forming cells)
b) chondroblasts (cartilage forming cells)
c) fibroblasts (fibrous tissue forming cells).
The mesenchymal tissue arises from two main sources: the sclerotomes of somites (paraxial mesoderm) and the somatic layer of lateral plate mesoderm (figure 2 and 3).
a) osteoblasts (bone forming cells)
b) chondroblasts (cartilage forming cells)
c) fibroblasts (fibrous tissue forming cells).
The mesenchymal tissue arises from two main sources: the sclerotomes of somites (paraxial mesoderm) and the somatic layer of lateral plate mesoderm (figure 2 and 3).
The Paraxial mesoderm forms the somites. The somites has three components :
Sclerotome (cartilage and bone), Dermatome (skin), and Myotome (muscle)
In most bones, the mesenchymal cells give cartilaginous model. Then, this model is replaced by bone via a process called cartilaginous ossification. However, in some bones such as the flat bone of the skull, the mesenchymal cells give rise to a fibrous membrane that becomes ossified via a process called membranous ossification.