osteocyte

An osteoblast that has been surrounded by a calcified interstitial substance; the cells are enclosed within lacunae, and the cytoplasmic processes extend through apertures of the lacunae into canaliculi in the bone. Like the osteoblast, the osteocyte may undergo transformations and assume the form of an osteoclast or reticular cell.

A spider-shaped, mature bone cell derived from an osteoblast. Osteocytes lie in a small cavities (the lacunae) in bone.

An osteoblast that has become embedded within the bone matrix, occupying a bone lacuna, and sending through canaliculi cytoplasmic processes that connect with other osteocytes in developing bone.

• o.–osteoblast pump — the interaction of osteocytes and osteoblasts, in response to parathyroid hormone, in moving calcium from the bone fluid to the extracellular fluid compartment.
• surface o. — a leaky barrier between cancellous and dense bone and lining the vascular channels in cortical bone. Called also resting osteoblast, inactive osteoblast.

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Transverse Section Of Bone

An osteocyte, a star-shaped cell, is the most abundant^{[citation needed]} cell found in compact bone. Cells contain a nucleus and a thin ring of cytoplasm. When osteoblasts become trapped in the matrix they secrete, they become osteocytes. Osteocytes are networked to each other via long cytoplasmic extensions that occupy tiny canals called canaliculi, which are used for exchange of nutrients and waste. The space that an osteocyte occupies is called a lacuna (Latin for a pit). Although osteocytes have reduced synthetic activity and, like osteoblasts are not capable of mitotic division, they are actively involved in the routine turnover of bony matrix, through various mechanosensory mechanisms. They destroy bone through a rapid, transient (relative to osteoclasts) mechanism called osteocytic osteolysis.  Osteoblasts/osteocytes develop in mesenchyme. Hydroxyapatite, calcium carbonate and calcium phosphate is deposited around the cell.

External links

• Histology at BU 02003loa - "Cartilage and Bone and Bone Histogenesis: cells of* Histology at BU 02705loa - "Cartilage and Bone and Bone Histogenesis: compact bone"* Histology at ou.edu

v • d • e Musculoskeletal system · connective tissue: bone and cartilage (TA A02.0 · GA 2.86-95) Cartilage perichondrium · fibrocartilage callus · metaphysis cells (chondroblast · chondrocyte) types (hyaline · elastic · fibrous) Bone Ossification intramembranous · endochondral Cycle osteoblast · osteoid · osteocyte · osteoclast Types cancellous · cortical Regions subchondral bone · epiphysis · epiphyseal plate/metaphysis · diaphysis · Condyle · Epicondyle Structure osteon / Haversian system · Haversian canals · Volkmann's canals · connective tissue (endosteum · periosteum) · Sharpey's fibres · enthesis · lacunae · canaliculi · trabeculae · medullary cavity · bone marrow Shapes long · short · flat · irregular · sesamoid bone and cartilage navs: anat/physio/dev, noncongen/congen/neoplasia, symptoms+signs/eponymous signs, proc

v • d • e Human cell types Blood/immune lymphoid: B cell  · T cell (Cytotoxic T cell, Natural Killer T cell, Regulatory T cell, T helper cell) · Natural killer cell myeloid: granulocytes (Basophil granulocyte, Eosinophil granulocyte, Neutrophil granulocyte/Hypersegmented neutrophil)  · Monocyte/Macrophage  · Red blood cell (Reticulocyte)  · Mast cell  · Thrombocyte/Megakaryocyte  · Dendritic cell Endocrine system thyroid (Thyroid epithelial cell, Parafollicular cell)  · parathyroid (Parathyroid chief cell, Oxyphil cell)  · adrenal (Chromaffin cell) · pineal (Pinealocyte) Nervous system glial cells: Glioblast (Astrocyte, Oligodendrocyte) · Microglia Magnocellular neurosecretory cell  · Stellate cell · Boettcher cell pituitary (Gonadotrope, Corticotrope, Thyrotrope, Somatotrope, Lactotroph ) Respiratory system Pneumocyte (Type I pneumocyte, Type II pneumocyte) · Clara cell · Goblet cell · Alveolar macrophage Circulatory system Myocardiocyte · Pericyte Digestive system stomach (Gastric chief cell, Parietal cell) · Goblet cell · Paneth cell G cells · D cells · ECL cells · I cells  · K cells  · S cells Enteroendocrine cells · Enterochromaffin cell · APUD cell liver (Hepatocyte, Kupffer cell) Cartilage/bone/ muscle/ integumentary system bone: Osteoblast · Osteocyte · Osteoclast · teeth (Cementoblast, Ameloblast) cartilage: Chondroblast · Chondrocyte skin/hair: Trichocyte · Keratinocyte  · Melanocyte (Nevus cell) muscle: Myocyte other: Adipocyte  · Fibroblast · Tendon cell Urinary system Podocyte  · Juxtaglomerular cell  · Intraglomerular mesangial cell/Extraglomerular mesangial cell  · Kidney proximal tubule brush border cell  · Macula densa cell Reproductive system male (Spermatozoon, Sertoli cell, Leydig cell)  · female (Ovum) see also list of distinct cell types in the adult human body

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