Search results
Results from the WOW.Com Content Network
Components that are essential for osteoblast bone formation include mesenchymal stem cells (osteoblast precursor) and blood vessels that supply oxygen and nutrients for bone formation. Bone is a highly vascular tissue, and active formation of blood vessel cells, also from mesenchymal stem cells, is essential to support the metabolic activity of ...
Bone is resorbed by osteoclasts, and is deposited by osteoblasts in a process called ossification. [6] Osteocyte activity plays a key role in this process. Conditions that result in a decrease in bone mass can either be caused by an increase in resorption or by a decrease in ossification. During childhood, bone formation exceeds resorption.
The osteoblast then deposits calcium phosphate which is hardened by hydroxide and bicarbonate ions. The brand-new bone created by the osteoblast is called osteoid. [24] Once the osteoblast is finished working it is actually trapped inside the bone once it hardens. When the osteoblast becomes trapped, it becomes known as an osteocyte.
After the bone is completely ossified, the osteoblasts retract their calcium phosphate secreting tendrils, leaving tiny canals in the bony matrix, known as canaliculi. These canaliculi provide the nutrients needed for the newly transformed osteoblasts, which are now called osteocytes. These cells are responsible for the general maintenance of ...
Diagram showing stages of endochondral ossification. Endochondral ossification is the formation of long bones and other bones. This requires a hyaline cartilage precursor. There are two centers of ossification for endochondral ossification. The primary center. In long bones, bone tissue first appears in the diaphysis (middle of shaft).
When osteoblasts become trapped in the matrix they secrete, they differentiate into osteocytes. Osteoblasts continue to line up on the surface which increases the size. As growth continues, trabeculae become interconnected and trabecular bone is formed. The term primary spongiosa is also used to refer to the initial trabecular network.
The initiation of endochondral ossification starts by proliferation and condensation of mesenchymal cells in the area where the bone will eventually be formed. Subsequently, these mesenchymal progenitor cells differentiate into chondroblasts, which actively synthesize cartilage matrix components.
Diagram of a typical long bone showing both compact (cortical) and cancellous (spongy) bone. Osteons on cross-section of a bone. In osteology, the osteon or haversian system (/ h ə ˈ v ɜːr. ʒ ən /; named for Clopton Havers) is the fundamental functional unit of much compact bone.