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25-461: Arcellinid testate amoebae or Arcellinida , Arcellacean or lobose testate amoebae are single-celled protists partially enclosed in a simple test (shell). Arcellinid testate amoebae are commonly found in soils, leaf litter , peat bogs and near/in fresh water. They use their pseudopodia , a temporary cell extension, for moving and taking in food. Like most amoebae, they are generally believed to reproduce asexually via binary fission. However

50-444: A strangler fig around a host tree, with tendrils fusing together to form a mesh, is called anastomosing. In geology , veins of quartz (or other) minerals can display anastomosis. Ductile shear zones frequently show anastomosing geometries of highly- strained rocks around lozenges of less-deformed material. Molten lava flows sometimes flow in anastomosed lava channels or lava tubes . In cave systems, anastomosis

75-450: A combination of both. Past environmental changes can be determined by analysing the composition of fossil tests, including the reconstruction of past climate change . Testate amoebae species have been used to reconstruct hydrological changes over the late Holocene , as a result of individual species possessing a narrow tolerance for ecohydrological conditions such as water-table depth or pH. Fossils of arcellinid testate amoebae date back to

100-437: A connection may be normal (such as the foramen ovale in a fetus' heart ) or abnormal (such as the patent foramen ovale in an adult's heart); it may be acquired (such as an arteriovenous fistula ) or innate (such as the arteriovenous shunt of a metarteriole ); and it may be natural (such as the aforementioned examples) or artificial (such as a surgical anastomosis ). The reestablishment of an anastomosis that had become blocked

125-937: A large blood supply, thus helping regulate systemic blood flow . Surgical anastomosis occurs when segments of intestine , blood vessel, or any other structure are connected together surgically (anastomosed). Examples include arterial anastomosis in bypass surgery , intestinal anastomosis after a piece of intestine has been resected, Roux-en-Y anastomosis and ureteroureterostomy . Surgical anastomosis techniques include linear stapled anastomosis, hand sewn anastomosis, end-to-end anastomosis (EEA). Anastomosis can be performed by hand or with an anastomosis assist device. Studies have been performed comparing various anastomosis approaches taking into account surgical "time and cost, postoperative anastomotic bleeding, leakage, and stricture". Pathological anastomosis results from trauma or disease and may involve veins , arteries , or intestines . These are usually referred to as fistulas . In

150-415: A morphologically similar mycelial wave front that continues to grow and explore. The significant difference is that each septated unit is binucleate, containing two unfused nuclei , i.e. one from each parent that eventually undergoes karyogamy and meiosis to complete the sexual cycle. Also the term "anastomosing" is used for mushroom gills which interlink and separate to form a network. The growth of

175-577: A recent review suggests that sexual recombination may be the rule rather than the exception in amoeboid protists in general, including the Arcellinid testate amoebae. Arcellinida always have a shell or testa. The tests lie outside the cell membrane and consist of organic or mineral materials that are either secreted or incorporate external particles. The testa has a single main opening. Simple tests are made by secretion (autogenous tests), agglutination of foreign material (xenogenous tests), or sometimes

200-418: Is actually composed of several, unrelated groups of organisms. However, some features they all share that have been used to group them together include the presence of a test (regardless of its composition) and pseudopodia that do not anastomose . Testate amoebae can be found in most freshwater environments, including lakes, rivers, cenotes , as well as mires and soils. The strong and resistant nature of

225-399: Is called a reanastomosis. Anastomoses that are abnormal, whether congenital or acquired, are often called fistulas . The term is used in medicine , biology , mycology , geology , and geography . Anastomosis: medical or Modern Latin, from Greek ἀναστόμωσις, anastomosis, "outlet, opening", Greek ana- "up, on, upon", stoma "mouth", "to furnish with a mouth". Thus the -stom- syllable

250-425: Is cognate with that of stoma in botany or stoma in medicine . An anastomosis is the connection of two normally divergent structures. It refers to connections between blood vessels or between other tubular structures such as loops of intestine . In circulatory anastomoses , many arteries naturally anastomose with each other; for example, the inferior epigastric artery and superior epigastric artery , or

275-548: Is likely that the group has evolved minimally over the course of the Phanerozoic . Phryganellina Organoconcha Volnustoma Hyalospheniformes Excentrostoma Sphaerothecina Longithecina Phryganellina Organoconcha Volnustoma Hyalospheniformes Excentrosoma Cylindrothecina Longithecina Sphaerothecina The classification of Arcellinida, as of 2019: Arcellinida incertae sedis : Testate amoebae The test of some species

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300-483: Is produced entirely by the amoeba and may be organic, siliceous or calcareous depending on the species ( autogenic tests ), whereas in other cases the test is made up of particles of sediment collected by the amoeba which are then agglutinated together by secretions from within the cell ( xenogenic tests ). A few taxa ( Hyalospheniidae ) can build either type, depending on the circumstances and availability of foreign material. The assemblage referred to as "testate amoebae"

325-666: Is the splitting of cave passages that later reconnect. Anastomosing rivers , anastomosing streams consist of multiple channels that divide and reconnect and are separated by semi-permanent banks formed of cohesive material, such that they are unlikely to migrate from one channel position to another. They can be confused with braided rivers based on their planforms alone, but braided rivers are much shallower and more dynamic than anastomosing rivers. Some definitions require that an anastomosing river be made up of interconnected channels that enclose floodbasins, again in contrast with braided rivers. Rivers with anastomosed reaches include

350-634: The Foraminifera (both in Rhizaria). The Thecamoebida (Amoebozoa), with the genus Thecamoeba , despite their name, do not have tests. Euglyphid testate amoebae are closely related to the Foraminifera . Anastomosis An anastomosis ( / ə ˌ n æ s t ə ˈ m oʊ s ɪ s / , pl. : anastomoses ) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels , leaf veins , or streams . Such

375-681: The Tonian stage of the Proterozoic , around 789-759 million years ago. The fossils indicate that by 730 million years ago, arcellinids had already diversified into major lineages. Testate amoebae are theorized to be mostly polyphyletic (coming from more than one ancestral type), but testaceafilosea, one group of testate amoebae, are theorized to be monophyletic . Ancient tests of terrestrial fauna are commonly found in fossilized amber, although mid-Cretaceous testate amoeba (i.e., Diffligia , Cucurbitella ) have been found in ancient lake sediments. It

400-401: The liver in patients with portal hypertension , often resulting in hemorrhoids , esophageal varices , or caput medusae . In evolution , anastomosis is a recombination of evolutionary lineage. Conventional accounts of evolutionary lineage present themselves as the branching out of species into novel forms. Under anastomosis, species might recombine after initial branching out, such as in

425-513: The lobose Tubulinea , which include Arcellinida , Difflugina and Phryganellina (within the Amoebozoa ), and the filose Euglyphida (within the SAR supergroup ), although there are smaller groups that also include other testate amoebae. The following table includes a few examples of testate amoebae genera, and reflects their position within

450-522: The anterior and/or posterior communicating arteries in the Circle of Willis in the brain. The circulatory anastomosis is further divided into arterial and venous anastomosis. Arterial anastomosis includes actual arterial anastomosis (e.g., palmar arch , plantar arch ) and potential arterial anastomosis (e.g. coronary arteries and cortical branch of cerebral arteries ). Anastomoses also form alternative routes around capillary beds in areas that do not need

475-442: The bifurcating fungal hyphae can form true reticulating networks. By sharing materials in the form of dissolved ions , hormones , and nucleotides , the fungus maintains bidirectional communication with itself. The fungal network might begin from several origins; several spores (i.e. by means of conidial anastomosis tubes ), several points of penetration, each a spreading circumference of absorption and assimilation. Once encountering

500-415: The case of recent research that shows that ancestral populations along human and chimpanzee lineages may have interbred after an initial branching event. The concept of anastomosis also applies to the theory of symbiogenesis , in which new species emerge from the formation of novel symbiotic relationships. In mycology , anastomosis is the fusion between branches of the same or different hyphae . Hence

525-411: The cases of veins or arteries, traumatic fistulas usually occur between artery and vein. Traumatic intestinal fistulas usually occur between two loops of intestine (entero-enteric fistula) or intestine and skin (enterocutaneous fistula). Portacaval anastomosis , by contrast, is an anastomosis between a vein of the portal circulation and a vein of the systemic circulation , which allows blood to bypass

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550-424: The classification by Adl et al. (2012), where five supergroups ( Amoebozoa , Opisthokonta , Excavata , SAR and Archaeplastida ) were proposed to classify all eukaryotes . This classification purposefully avoids the use of Linnaean higher category names (phylum, class, order, family). While it has been noted that the names that Adl et al. provide for the clades may result confusing or uninformative regarding

575-599: The relative degree of phenotypic distinctiveness amongst groups when used in isolation, this system avoids creating superfluous ranks where unnecessary and provides stable group names that can be retained even when a group is moved to a different lineage , as is often the case with protists, as their classification remains in constant review. Plagiopyxis - Quadrulella - Trigonopyxis Traditionally, those species that form large networks of anastomosing pseudopodia , despite some of them having tests, are not counted amongst testate amoebae; this comprises genus Gromia and

600-400: The tests allows them to be preserved long after the amoeba has died. These characteristics, along with the sensitivity that some species display to changes in environmental conditions (such as temperature, pH, and conductivity), has sparked their use as bioindicators and paleoclimate proxies in recent years. Testate amoebae are a polyphyletic assemblage. The main testate amoebae groups are

625-427: The tip of another expanding, exploring self, the tips press against each other in pheromonal recognition or by an unknown recognition system, fusing to form a genetic singular clonal colony that can cover hectares called a genet or just microscopical areas. For fungi, anastomosis is also a component of reproduction. In some fungi, two different haploid mating types – if compatible – merge. Somatically , they form

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