What Is Osteoblast?
Osteoblast is a large cell responsible for the synthesis and mineralization of bone during both initial bone formation and later bone remodeling. Osteoblasts are a major cellular component of bone, it form a closely packed sheet on the surface of the bone, from which cellular processes extend through the developing bone. They arise from differentiation of osteogenic cells in periosteum (tissue that covers the outer surface of the bone) and in the endosteum of the marrow cavity.
The osteoblasts produce many cell products such as, collagen, growth factors, enzymes (alkaline phosphatase and collagenase) and hormones (osteocalcin and osteopontin) which compose the organic matrix of bone. Also the osteoblasts produce the bone mineral (hydroxylapatite) that is deposited in some regulated manner into the organic matrix forming a strong and dense mineralized tissue.
What You Need To Know About Osteoblast
- Osteoblast is a large cell responsible for synthesis and mineralization of bone during both initial bone formation and later bone remodeling.
- Osteoblasts are the major cellular component of bone, usually involved in the initial formation and mineralization of bones.
- The osteoblasts, the bone cell responsible for forming new bone, it is found in the growing portions of bone, including the periosteum and endosteum.
- The osteoblasts produce many cell products, including the enzymes alkaline phosphatase, collagenese, growth factors and hormones such as osteocalcin.
- Osteoblasts develop from the differentiation of osteogenic cells in periosteum (tissue that covers the outer surface of the bone) and the endosteum of marrow cavity.
- Osteoblasts are smaller, uninucleated cells (cells with only one nucleus).
- The cells possess lesser number of mitochondria, vacuoles and lysosomes.
- Osteoblasts are derived from pluripotent mesenchymal stem cells.
- At the end of bone formation, osteoblasts become osteocytes.
- In osteoblasts, cells produce large amount of alkaline phosphatase enzyme.
- Osteoblasts are surrounded by the growing bone matrix and as the material calcifies, the cell is trapped in a space referred to as lacuna.
Given that bone is a dynamic tissue that is continuously being broken down and restructured in response to such influences as structural stress and the body’s requirement for calcium, the osteoclast is the cell responsible for removing both organic and inorganic components of bone through dissolution and absorption of bone. Osteoclasts are multinucleated cells formed by the fusion of many cells derived from circulating monocytes in the blood.
Osteoclasts produce a number of enzymes such as acid phosphatase that dissolve both the organic collagen and the inorganic calcium and phosphorous of the bone. Mineralized bone is first broken into fragments; the osteoclast then engulfs the fragments and digests them within cytoplasmic vacuoles. Calcium and phosphorous liberated by the breakdown of the mineralized bone are released into the bloodstream. Unmineralized bone, usually referred to as osteoid is protected against osteoclastic resorption.
What You Need To Know About Osteoclast
- Osteoclast is a type of bone cell that breaks down bone tissue. This is usually a critical process in the maintenance, repair and remodeling of bones of the vertebral skeleton.
- Osteoclasts are a type of cells of bone that are responsible for the resorption of bone. Bone resorption is a process whereby an acid collagenase is secreted by osteoclast to disassemble and digest the composite of hydrated protein and mineral at molecular level.
- Osteoblasts are involved in the bone breakdown and bone resorption.
- Osteoclasts are characterized by a cytoplasm with a homogeneous “foamy appearance”. The appearance is usually due to high concentration of vesicles and vacuoles.
- Osteoclasts develop from monocytes or macrophages.
- Osteoclasts formation requires the presence of membrane bound proteins, RANKL (receptor activator of nuclear factor kβ ligand) and M-CSF (Microphage colony-stimulating factor).
- Osteoclasts are large, multi-nucleated cells (cells with more than one nucleus). The human osteoclasts on bone typically have five nuclei and are 150-200µm in diameter.
- The cells possess larger number of mitochondria, vacuoles and lysosomes.
- In osteoclast, rough endoplasmic reticulum is sperse and the Golgi complex is extensive.
- Osteoclasts are derived from hematopoietic cells of granulocyte-macrophage lineage.
- At the end of bone formation, osteoclasts do not become osteocytes.
- In osteoclasts, cells produce large amount of tartrate resistant acid phosphatase enzyme.
Also Read: Difference Between Ligament And Tendon
Difference Between Osteoblasts And Osteoclasts In Tabular Form
|BASIS OF COMPARISON||OSTEOBLAST||OSTEOCLASTS|
|Describe||Osteoblasts are cells forming bone and originate from cells osteoprogenitor mesenchymal and are involved in the process of remodeling bone.||Osteoclasts are a type of cells of bone that are responsible for the resorption of bone.|
|Involvement||They are usually involved in the formation and mineralization of bones.||They are involved in the bone breakdown and bone resorption.|
|Development||They develop from the osteogenic cells.||They develop from monocytes or macrophages.|
|Location||In bone, osteoclasts are found in pits in the bone surface which are referred to as resorption bays or Howship’s lacunae.|
|Size||They are smaller, uninucleated cells.||They are large, multi-nucleated cells.|
|Number Of Mitochondria , Vacuoles And Lysosomes||The cells possess lesser number of mitochondria, vacuoles and lysosomes.||The cells possess larger number of mitochondria, vacuoles and lysosomes.|
|Derivation||They are derived from pluripotent mesenchymal stem cells.||They are derived from hematopoietic cells of granulocyte-macrophage lineage.|
|At the End of Bone Formation||At the end of bone formation, osteoblasts become osteocytes.||At the end of bone formation, osteoclasts do not become osteocytes.|
|Enzyme Production||In osteoblasts, cells produce large amount of alkaline phosphatase enzyme and collagenase.||In osteoclasts, cells produce large amount of tartrate resistant acid phosphatase enzyme.|
|Hormone Production||Osteoblasts are regulated by hormones such as osteocalcin and osteopontin.||Osteoclasts are regulated by several hormones including parathyroid hormone (PTH) from parathyroid gland, calcitonin from the thyroid gland and growth factor interleukin.|
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