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Epithelial Cell Rests Of Malassez
In dentistry, the epithelial cell rests of Malassez (ERM) or epithelial rests of Malassez (''pax epithelialis pediodontii'') are part of the periodontal ligament cells around a tooth. They are discrete clusters of residual cells from Hertwig's epithelial root sheath (HERS) that didn't completely disappear. It is considered that these cell rests proliferate to form epithelial lining of various odontogenic cysts such as radicular cyst under the influence of various stimuli. They are named after Louis-Charles Malassez (1842–1909) who described them. Some rests become calcified in the periodontal ligament (cementicles). ERM plays a role in cementum repair and regeneration. The stem cells in ERM can undergo an epithelial–mesenchymal transition and differentiate into diverse types of cells of mesodermal and ectodermal The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hertwig's Epithelial Root Sheath
The Hertwig epithelial root sheath (HERS) or epithelial root sheath is a proliferation of epithelial cells located at the cervical loop of the enamel organ in a developing tooth. Hertwig epithelial root sheath initiates the formation of dentin in the root of a tooth by causing the differentiation of odontoblasts from the dental papilla. The root sheath eventually disintegrates with the periodontal ligament, but residual pieces that do not completely disappear are seen as epithelial cell rests of Malassez (ERM). These rests can become cystic, presenting future periodontal infections. Structure Hertwig epithelial root sheath is derived from the inner and outer enamel epithelium of the enamel organ.Illustrated Dental Embryology, Histology, and Anatomy, Bath-Balogh and Fehrenbach, Elsevier, 2011, p. 66 Function The sheath is also responsible for multiple or accessory roots (medial growth) and lateral or accessory canals in the root (break in epithelium).Ten Cate's Oral Histology ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HERS
{{Disambiguation, surnam ...
Hers may refer to: * The possessive pronoun version of she * Two rivers in southern France: ** Hers-Vif (also: ''Grand Hers'' or ''Hers'') ** Hers-Mort * The Georgian name for the indigenous people of Hereti, more commonly called Èrs * Her's, a former English rock band from Liverpool * Hims & Hers Health, a telemedicine company People with the surname: * François Hers (born 1943), Belgian photographer and artist * Henri G. Hers (1923–2008), Belgian scientist HERS may refer to: * Epithelial root sheath or Hertwig’s epithelial root sheath * Various energy rating systems: ** Home Energy Rating system in the United States ** House Energy Rating scheme in Australia See also * Her (other) Her is the objective and possessive form of the English-language feminine pronoun she. Her, HER or H.E.R. may also refer to: Arts, entertainment and media Music * H.E.R. (born 1997), American singer ** ''H.E.R.'' (album), 2017 * HIM (Finnish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periodontal Ligament
The periodontal ligament, commonly abbreviated as the PDL, is a group of specialized connective tissue fibers that essentially attach a tooth to the alveolar bone within which it sits. It inserts into root cementum one side and onto alveolar bone on the other. Structure The PDL consists of principal fibres, loose connective tissue, blast and clast cells, oxytalan fibres and Cell Rest of Malassez. Alveolodental ligament The main principal fiber group is the alveolodental ligament, which consists of five fiber subgroups: alveolar crest, horizontal, oblique, apical, and interradicular on multirooted teeth. Principal fibers other than the alveolodental ligament are the transseptal fibers. All these fibers help the tooth withstand the naturally substantial compressive forces that occur during chewing and remain embedded in the bone. The ends of the principal fibers that are within either cementum or alveolar bone proper are considered Sharpey fibers. * Alveolar crest fibers ('' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tooth
A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tearing food, for defensive purposes, to intimidate other animals often including their own, or to carry prey or their young. The roots of teeth are covered by gums. Teeth are not made of bone, but rather of multiple tissues of varying density and hardness that originate from the embryonic germ layer, the ectoderm. The general structure of teeth is similar across the vertebrates, although there is considerable variation in their form and position. The teeth of mammals have deep roots, and this pattern is also found in some fish, and in crocodilians. In most teleost fish, however, the teeth are attached to the outer surface of the bone, while in lizards they are attached to the inner surface of the jaw by one side. In cartilaginous fish, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Odontogenic Cyst
Odontogenic cyst are a group of jaw cysts that are formed from tissues involved in odontogenesis (tooth development). Odontogenic cysts are closed sacs, and have a distinct membrane derived from rests of odontogenic epithelium. It may contain air, fluids, or semi-solid material. Intra-bony cysts are most common in the jaws, because the mandible and maxilla are the only bones with epithelial components. That odontogenic epithelium is critical in normal tooth development. However, epithelial rests may be the origin for the cyst lining later. Not all oral cysts are odontogenic cyst. For example, mucous cyst of the oral mucosa and nasolabial duct cyst are not of odontogenic origin. In addition, there are several conditions with so-called (radiographic) 'pseudocystic appearance' in jaws; ranging from anatomic variants such as Stafne static bone cyst, to the aggressive aneurysmal bone cyst. Classification *I. Cysts of the jaws **A. Epithelial-lined cysts ***1. Developmental origin ** ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radicular Cyst
Radicular pain, or radiculitis, is pain "radiated" along the dermatome (sensory distribution) of a nerve due to inflammation or other irritation of the nerve root (radiculopathy) at its connection to the spinal column. A common form of radiculitis is sciatica – radicular pain that radiates along the sciatic nerve from the lower spine to the lower back, gluteal muscles, back of the upper thigh, calf, and foot as often secondary to nerve root irritation from a spinal disc herniation or from osteophytes in the lumbar region of the spine. Friday, 20 January 2017 Radiculitis indicates inflammation of the spinal nerve root, which may lead to pain in that nerve's distribution without weakness as opposed to radiculopathy. When the radiating pain is associated with numbness or weakness, the diagnosis is radiculopathy if the lesion is at the nerve root and myelopathy if at the spinal cord itself. See also * Intervertebral disc * Sciatica * Spinal disc herniation * Arachnoiditis Arach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Louis-Charles Malassez
Louis-Charles Malassez (21 September 1842 – 22 December 1909) was a French anatomist and histologist born in Nevers, department of Nièvre. He studied medicine in Paris, where he worked as an ''interne'' from 1867. He served with the 5th Ambulance Corps during the Franco-Prussian War, afterwards returning to Paris, where he worked with distinguished physicians that included Claude Bernard, Jean-Martin Charcot and Pierre Potain. In 1875, he attained the chair of anatomy at Collège de France, and in 1894 he became a member of the ''Académie de Médecine''. He conducted histological research of the blood, and is credited for design of the hemocytometer, a device used to quantitatively measure blood cells. In the field of dentistry, he described residual cells of the epithelial root sheath in the periodontal ligament. These remaining cells are referred to as epithelial cell rests of Malassez (ERM). A genus of fungi called ''Malassezia'' bears his name. The species in the genus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cementicle
A cementicle is a small, spherical or ovoid calcified mass embedded within or attached to the cementum layer on the root surface of a tooth, or lying free within the periodontal ligament. They tend to occur in elderly individuals. There are 3 types: * Free cementicle – not attached to cementum * Attached (sessile) cementicle – attached to the cementum surface (also termed exocementosis) * Embedded (interstitial) cementicle – with advancing age the cementum thickens, and the cementicle may become incorporated into the cementum layer They may be visible on a radiograph (x-ray). They may appear singly or in groups, and are most commonly found at the tip of the root. Their size is variable, but generally they are small (about 0.2 mm – 0.3 mm in diameter). Cementicles are usually acellular, and may contain either fibrillar or afibrillar cementum, or a mixture of both. Cementicles are the result of dystrophic calcification, but the reason why this takes place is unclear. Ceme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epithelial
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellular matrix. Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs. An example is the epidermis, the outermost layer of the skin. There are three principal shapes of epithelial cell: squamous (scaly), columnar, and cuboidal. These can be arranged in a singular layer of cells as simple epithelium, either squamous, columnar, or cuboidal, or in layers of two or more cells deep as stratified (layered), or ''compound'', either squamous, columnar or cuboidal. In some tissues, a layer of columnar cells may appear to be stratified due to the placement of the nuclei. This sort of tissue is called pseudostratified. All glands are made up of epitheli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesenchymal
Mesenchyme () is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood or bone. The interactions between mesenchyme and epithelium help to form nearly every organ in the developing embryo. Vertebrates Structure Mesenchyme is characterized morphologically by a prominent ground substance matrix containing a loose aggregate of reticular fibers and unspecialized mesenchymal stem cells. Mesenchymal cells can migrate easily (in contrast to epithelial cells, which lack mobility), are organized into closely adherent sheets, and are polarized in an apical-basal orientation. Development The mesenchyme originates from the mesoderm. From the mesoderm, the mesenchyme appears as an embryologically primitive "soup". This "soup" exists as a combination of the mesenchymal cells plus serous fluid plus the many different tissue proteins. Serous fluid is typically stocked with the many serous elements, such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesodermal
The mesoderm is the middle layer of the three germ layers that develops during gastrulation in the very early development of the embryo of most animals. The outer layer is the ectoderm, and the inner layer is the endoderm.Langman's Medical Embryology, 11th edition. 2010. The mesoderm forms mesenchyme, mesothelium, non-epithelial blood cells and coelomocytes. Mesothelium lines coeloms. Mesoderm forms the muscles in a process known as myogenesis, septa (cross-wise partitions) and mesenteries (length-wise partitions); and forms part of the gonads (the rest being the gametes). Myogenesis is specifically a function of mesenchyme. The mesoderm differentiates from the rest of the embryo through intercellular signaling, after which the mesoderm is polarized by an organizing center. The position of the organizing center is in turn determined by the regions in which beta-catenin is protected from degradation by GSK-3. Beta-catenin acts as a co-factor that alters the activity of the tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ectodermal
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from the outer layer of germ cells. The word ectoderm comes from the Greek ''ektos'' meaning "outside", and ''derma'' meaning "skin".Gilbert, Scott F. Developmental Biology. 9th ed. Sunderland, MA: Sinauer Associates, 2010: 333-370. Print. Generally speaking, the ectoderm differentiates to form epithelial and neural tissues (spinal cord, peripheral nerves and brain). This includes the skin, linings of the mouth, anus, nostrils, sweat glands, hair and nails, and tooth enamel. Other types of epithelium are derived from the endoderm. In vertebrate embryos, the ectoderm can be divided into two parts: the dorsal surface ectoderm also known as the external ectoderm, and the neural plate, which invaginates to form the neural tube and neural crest. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
