Light micrograph of an osteoclast displaying typical distinguishing characteristics: a large cell with multiple nuclei and a "foamy" cytosol.
Illustration showing a single osteoclast
Details
Precursor
osteoclast progenitors
Location
Bone
Function
Breakdown of bone tissue
Identifiers
Latin
osteoclastus
MeSH
D010010
TH
H2.00.03.7.00005
FMA
66781
Anatomical terms of microanatomy
[edit on Wikidata]
An osteoclast (from Ancient Greek ὀστέον (osteon) 'bone', and κλαστός (clastos) 'broken') is a type of bone cell that breaks down bone tissue. This function is critical in the maintenance, repair, and remodeling of bones of the vertebral skeleton. The osteoclast disassembles and digests the composite of hydrated protein and mineral at a molecular level by secreting acid and a collagenase, a process known as bone resorption. This process also helps regulate the level of blood calcium.
Osteoclasts are found on those surfaces of bone that are undergoing resorption. On such surfaces, the osteoclasts are seen to be located in shallow depressions called resorption bays (Howship's lacunae). The resorption bays are created by the erosive action of osteoclasts on the underlying bone. The border of the lower part of an osteoclast exhibits finger-like processes due to the presence of deep infoldings of the cell membrane; this border is called ruffled border. The ruffled border lies in contact with the bone surface within a resorption bay. The periphery of the ruffled border is surrounded by a ring-like zone of cytoplasm which is devoid of cell organelles but is rich in actin filaments. This zone is called clear zone or sealing zone. The actin filaments enable the cell membrane surrounding the sealing zone to be anchored firmly to the bony wall of Howship's lacunae. In this way, a closed subosteoclastic compartment is created between the ruffled border and the bone that is undergoing resorption. The osteoclasts secrete hydrogen ions, collagenase, cathepsin K and hydrolytic enzymes into this compartment. Resorption of bone matrix by the osteoclasts involves two steps: (1) dissolution of inorganic components (minerals), and (2) digestion of organic component of the bone matrix. The osteoclasts pump hydrogen ions into subosteoclastic compartment and thus create an acidic microenvironment, which increases solubility of bone mineral, resulting in the release and re-entry of bone minerals into the cytoplasm of osteoclasts to be delivered to nearby capillaries. After the removal of minerals, collagenase and gelatinase are secreted into the subosteoclastic compartment. These enzymes digest and degrade collagen and other organic components of decalcified bone matrix. The degradation products are phagocytosed by osteoclasts at the ruffled border. Because of their phagocytic properties, osteoclasts are considered to be a component of the mononuclear phagocyte system (MPS). The activity of osteoclasts is controlled by hormones and cytokines. Calcitonin, a hormone of thyroid gland, suppresses the osteoclastic activity. The osteoclasts do not have receptors for parathyroid hormone (PTH). However, PTH stimulates the osteoblasts to secrete the cytokine called osteoclast-stimulating factor, which is a potent stimulator of the osteoclastic activity.[1]
An odontoclast (/odon·to·clast/; o-don´to-klast) is an osteoclast associated with absorption of the roots of deciduous teeth.[2][3][4]
^Medical Histology by Laiq Hussain Siddiqui (6th Edition)
^"Odontoclast". Farlex, The Free Dictionary. 2007. Retrieved 2013-11-06.
^Wang Z, McCauley LK (March 2011). "Osteoclasts and odontoclasts: signaling pathways to development and disease". Oral Diseases. 17 (2): 129–42. doi:10.1111/j.1601-0825.2010.01718.x. PMID 20659257.
^Chatterjee K (1 December 2006). Essentials of Oral Histology. Jaypee Brothers Publishers. p. 155. ISBN 978-81-8061-865-9.[permanent dead link]
An osteoclast (from Ancient Greek ὀστέον (osteon) 'bone', and κλαστός (clastos) 'broken') is a type of bone cell that breaks down bone tissue. This function...
resorption is resorption of bone tissue, that is, the process by which osteoclasts break down the tissue in bones and release the minerals, resulting in...
activation-induced cytokine (TRANCE), osteoprotegerin ligand (OPGL), and osteoclast differentiation factor (ODF), is a protein that in humans is encoded by...
osteocytes are involved in the formation and mineralisation of bone; osteoclasts are involved in the resorption of bone tissue. Modified (flattened) osteoblasts...
body. Osteoclasts are frequently classified and discussed separately from other MGCs which are more closely linked with disease. Non-osteoclast MGCs can...
Chambers he developed the osteoclast lacunar bone resorption assay system. His work was the first to show that the human osteoclast shares specific surface...
responsible for bone metabolism: osteoblasts (which secrete new bone), and osteoclasts (which break bone down). The structure of bones as well as adequate supply...
Osteoclast stimulatory transmembrane protein is a protein that in humans is encoded by the OCSTAMP gene. GRCh38: Ensembl release 89: ENSG00000149635 –...
New bone is deposited by osteoblast cells and resorbed or destroyed by osteoclast cells. This addition and subtraction of bone usually yields no net change...
NF-κB ligand (RANKL)–induced osteoclast differentiation. Pepstatin A suppresses the formation of multinuclear osteoclasts dose-dependently. This inhibition...
osteoblasts creating bone and osteoclasts destroying bone. Bisphosphonates inhibit the digestion of bone by encouraging osteoclasts to undergo apoptosis, or...
expressed by cells in the monocyte lineage (e.g., monocytic phagocytes, osteoclasts), by circulating macrophages, and by tissue macrophages (e.g., Kupffer...
understood. It is postulated that osteoclasts are the cells responsible for the resorption of the root surface. Osteoclasts can break down bone, cartilage...
during the differentiation of osteoclast precursor cells into mature osteoclasts, known as osteoclastogenesis. Mature osteoclasts then bind to bone through...
increased tubular reabsorption of calcium and activation of osteoclast activity, respectively. Osteoclasts are a type of bone cell which cause bone resorption...
neutralize excessive existing acid. Hydrochloric acid is also used by osteoclasts alongside proteases for bone resorption. Being a strong acid, hydrochloric...
shown to stimulate osteoclast differentiation and function. Studies have found that blockade of the A1 Receptor suppresses the osteoclast function, leading...
factor kappa-Β ligand), which works by decreasing the development of osteoclasts, which are cells that break down bone. It was developed by the biotechnology...
tumor can be subclassified. Osteosarcomas may exhibit multinucleated osteoclast-like giant cells. X-rays is the initial imaging of choice to diagnose...
the periosteum. To prevent the bone from becoming unnecessarily thick, osteoclasts resorb the bone from the endosteal side. Long bone Netter, Frank H. (1987)...
of plasma B cells, T cells, dendritic cells (DCs), macrophages, and osteoclasts. Pattern Recognition Receptors (PRRs) can activate BLIMP-1, both as a...
dysplasias. The cause of the disease is understood to be malfunctioning osteoclasts and their inability to resorb bone. Although human osteopetrosis is a...
more differentiated myeloid cell types such as monocytes, macrophages, osteoclasts, myeloid dendritic cells, microglia, and Paneth cells. CSF1R expression...
Under normal conditions, bone undergoes continuous remodeling through osteoclast-mediated bone resorption and osteoblast-mediated bone deposition. These...
a syncytium. Cell fusion occurs during differentiation of myoblasts, osteoclasts and trophoblasts, during embryogenesis, and morphogenesis. Cell fusion...
mechanisms. They destroy bone through a rapid, transient (relative to osteoclasts) mechanism called osteocytic osteolysis. Hydroxyapatite, calcium carbonate...
active resorption of bone matrix by osteoclasts and can be interpreted as the reverse of ossification. Although osteoclasts are active during the natural formation...
and secrete matrix proteins and transport mineral into the matrix, and osteoclasts, which break down the tissues. Osteoblasts are the major cellular component...
maturity. In adults, somatomedin alteration contributes to increased osteoclast activity, resulting in weaker bones that are more prone to pathologic...
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