Periosteal Bone
Periosteal Bone
in vetebrates, a bone that originates without undergoing a cartilaginous stage. An aggregate of cells of skeletogenous mesenchyme form osteoblasts and then a bone. In the process of vertebrate evolution, most periosteal bones were formed from cutaneous scales embedded in the skin. Examples include the frontal and temporal bones (seeSUBSTITUTION BONE). [20–487–l]