An anastomosis (, plural 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 vein
A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...
s, or
stream
A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams are ...
s. Such a connection may be normal (such as the
foramen ovale in a fetus's heart) or abnormal (such as the
patent foramen ovale
Atrial septal defect (ASD) is a congenital heart defect in which blood flows between the atria (upper chambers) of the heart. Some flow is a normal condition both pre-birth and immediately post-birth via the foramen ovale; however, when this d ...
in an adult's heart); it may be acquired (such as an
arteriovenous fistula
An arteriovenous fistula is an abnormal connection or passageway between an artery and a vein. It may be congenital, surgically created for hemodialysis treatments, or acquired due to pathologic process, such as trauma or erosion of an arteria ...
) or innate (such as the arteriovenous shunt of a
metarteriole
A metarteriole is a short microvessel in the microcirculation that links arterioles and capillaries. Instead of a continuous tunica media, they have individual smooth muscle cells placed a short distance apart, each forming a precapillary sphi ...
); and it may be natural (such as the aforementioned examples) or artificial (such as a
surgical anastomosis
A surgical anastomosis is a surgical technique used to make a new connection between two body structures that carry fluid, such as blood vessels or bowel. For example, an arterial anastomosis is used in vascular bypass and a colonic anastomosis ...
). The reestablishment of an anastomosis that had become blocked is called a reanastomosis. Anastomoses that are abnormal, whether
congenital
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...
or acquired, are often called
fistula
A fistula (plural: fistulas or fistulae ; from Latin ''fistula'', "tube, pipe") in anatomy is an abnormal connection between two hollow spaces (technically, two epithelialized surfaces), such as blood vessels, intestines, or other hollow o ...
s.
The term is used in
medicine
Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care practice ...
,
biology
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary ...
,
mycology
Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans, including as a source for tinder, traditional medicine, food, and entheogens, as ...
,
geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...
, and
geography
Geography (from Greek: , ''geographia''. Combination of Greek words ‘Geo’ (The Earth) and ‘Graphien’ (to describe), literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, and ...
.
Etymology
Anastomosis: medical or Modern Latin, from Greek ἀναστόμωσις, anastomosis, "outlet, opening", Gr ana- "up, on, upon", stoma "mouth", "to furnish with a mouth". Thus the ''-stom-'' syllable is cognate with that of
''stoma'' in botany or
''stoma'' in medicine.
Medical anatomy
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
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans an ...
.
Circulatory
In
circulatory anastomoses, many arteries naturally anastomose with each other; for example, the
inferior epigastric artery
In human anatomy, inferior epigastric artery refers to the artery that arises from the external iliac artery. It anastomoses with the superior epigastric artery. Along its course, it is accompanied by a similarly named vein, the inferior epigas ...
and
superior epigastric artery
In human anatomy, the superior epigastric artery is a blood vessel that carries oxygenated blood to the abdominal wall, and upper rectus abdominis muscle. It is a branch of the internal thoracic artery. It enters the rectus sheath to descend upo ...
, or the anterior and/or posterior communicating arteries in the
Circle of Willis
The circle of Willis (also called Willis' circle, loop of Willis, cerebral arterial circle, and Willis polygon) is a circulatory anastomosis that supplies blood to the brain and surrounding structures in reptiles, birds and mammals, including huma ...
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
The plantar arch is a circulatory anastomosis formed from:
* deep plantar artery, from the dorsalis pedis - a.k.a. dorsal artery of the foot
* lateral plantar artery
The plantar arch supplies the underside, or sole, of the foot.
The plantar a ...
) and potential arterial anastomosis (e.g.
coronary arteries
The coronary arteries are the arterial blood vessels of coronary circulation, which transport oxygenated blood to the heart muscle. The heart requires a continuous supply of oxygen to function and survive, much like any other tissue or organ of ...
and cortical branch of
cerebral arteries
The cerebral arteries describe three main pairs of arteries and their branches, which perfuse the cerebrum of the brain.
The three main arteries are the:
* ''Anterior cerebral artery'' (ACA)
* ''Middle cerebral artery'' (MCA)
* ''Posterior cereb ...
). Anastomoses also form alternative routes around
capillary
A capillary is a small blood vessel from 5 to 10 micrometres (μm) in diameter. Capillaries are composed of only the tunica intima, consisting of a thin wall of simple squamous endothelial cells. They are the smallest blood vessels in the body: ...
beds in areas that don't need a large blood supply, thus helping regulate
systemic blood flow.
Surgical
Surgical anastomosis
A surgical anastomosis is a surgical technique used to make a new connection between two body structures that carry fluid, such as blood vessels or bowel. For example, an arterial anastomosis is used in vascular bypass and a colonic anastomosis ...
occurs when segments of
intestine
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans an ...
, blood vessel, or any other structure are connected together surgically (anastomosed). Examples include arterial anastomosis in
bypass surgery
Bypass surgery refers to a class of surgery involving rerouting a tubular body part.
Types include:
* Vascular bypass surgery such as coronary artery bypass surgery, a heart operation
* Cardiopulmonary bypass, a technique used in coronary arter ...
, intestinal anastomosis after a piece of intestine has been resected,
Roux-en-Y anastomosis
In general surgery, a Roux-en-Y anastomosis, or Roux-en-Y, is an end-to-side surgical anastomosis of bowel used to reconstruct the gastrointestinal tract. Typically, it is between stomach and small bowel that is distal (or further down the gastr ...
and
ureteroureterostomy
Ureteroureterostomy ( "urétero-uréte-róstomy") is end-to-end connection (anastomosis) of the two portions of a transected ureter; also called ureteroureteral anastomosis and van Hook operation (after Weller van Hook, surgeon).
__TOC__ Reasons ...
. 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
Pathological
Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in th ...
anastomosis results from
trauma
Trauma most often refers to:
*Major trauma, in physical medicine, severe physical injury caused by an external source
*Psychological trauma, a type of damage to the psyche that occurs as a result of a severely distressing event
*Traumatic inju ...
or
disease
A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that ar ...
and may involve
vein
Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated ...
s,
arteries
An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the p ...
, or
intestines
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...
. These are usually referred to as
fistula
A fistula (plural: fistulas or fistulae ; from Latin ''fistula'', "tube, pipe") in anatomy is an abnormal connection between two hollow spaces (technically, two epithelialized surfaces), such as blood vessels, intestines, or other hollow o ...
s. In 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
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other animal coverings, such as the arthropod exoskeleton, have different de ...
(enterocutaneous fistula).
Portacaval anastomosis
A portocaval anastomosis or porto-systemic anastomosis is a specific type of anastomosis that occurs between the veins of the portal circulation and those of the systemic circulation. When there is a blockage of the portal system, portocaval anas ...
, by contrast, is an anastomosis between a vein of the
portal circulation and a vein of the
systemic circulation
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
, which allows blood to bypass the
liver
The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it i ...
in patients with
portal hypertension
Portal hypertension is abnormally increased portal venous pressure – blood pressure in the portal vein and its branches, that drain from most of the intestine to the liver. Portal hypertension is defined as a hepatic venous pressure gradient gr ...
, often resulting in
hemorrhoids
Hemorrhoids (or haemorrhoids), also known as piles, are vascular structures in the anal canal. In their normal state, they are cushions that help with stool control. They become a disease when swollen or inflamed; the unqualified term ''he ...
,
esophageal varices
Esophageal varices are extremely dilated sub-mucosal veins in the lower third of the esophagus. They are most often a consequence of portal hypertension, commonly due to cirrhosis. People with esophageal varices have a strong tendency to develop s ...
, or
caput medusae
Caput medusae is the appearance of distended and engorged superficial epigastric veins, which are seen radiating from the umbilicus across the abdomen. The name ''caput medusae'' ( Latin for "head of Medusa") originates from the apparent simil ...
.
Biology
Evolution
In
evolution
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
, 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 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
Symbiogenesis (endosymbiotic theory, or serial endosymbiotic theory,) is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. The theory holds that mitochondria, plastids such as chloroplasts, and possibly ...
, in which new
species
In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
emerge from the formation of novel symbiotic relationships.
Mycology
In
mycology
Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans, including as a source for tinder, traditional medicine, food, and entheogens, as ...
, anastomosis is the fusion between branches of the same or different
hyphae
A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium.
Structure
A hypha consists of one or ...
. Hence the bifurcating fungal hyphae can form true reticulating networks. By sharing materials in the form of dissolved
ions
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
,
hormones
A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required fo ...
, and
nucleotides
Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules with ...
, 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 Conidial anastomosis tubes (CATs) are cells formed from the conidia (a type of fungal asexual spores) of many filamentous fungi. These cells have a tubular shape and form an anastomosis (bridge) that allows fusion between conidia.
CATs and germ tu ...
), several points of penetration, each a spreading circumference of absorption and assimilation. Once encountering 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
Genet or Genêt may refer to:
Aircraft
*Armstrong Siddeley Genet, aircraft engine
* Armstrong Siddeley Genet Major, aircraft engine
Animals and plants
* Genet (biology), a colony of plants, fungi or bacteria that come from a single genetic sourc ...
or just microscopical areas.
For fungi, anastomosis is also a component of reproduction. In some fungi, two different
haploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respecti ...
mating types – if compatible – merge.
Somatically, they form 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
Karyogamy is the final step in the process of fusing together two haploid eukaryotic cells, and refers specifically to the fusion of the two nuclei. Before karyogamy, each haploid cell has one complete copy of the organism's genome. In order for ...
and meiosis to complete the sexual cycle.
Also the term "anastomosing" is used for mushroom gills which interlink and separate to form a network.
Botany
The growth of a
strangler fig
Strangler fig is the common name for a number of tropical and subtropical plant species in the genus ''Ficus'', including those that are commonly known as banyans. Some of the more well-known species are:
* '' Ficus altissima''
* ''Ficus aurea'', ...
around a host tree, with tendrils fusing together to form a mesh, is called anastomosing.
Geology
In
geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...
, anastomosis refers to
quartz
Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical fo ...
(or other)
veins
Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated ...
displaying this property, which is often related to
shearing in
metamorphic
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...
regions.
Geography
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 river
A braided river, or braided channel, consists of a network of river channels separated by small, often temporary, islands called braid bars or, in English usage, '' aits'' or ''eyots''.
Braided streams tend to occur in rivers with high sediment ...
s 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 the
Magdalena River
The Magdalena River ( es, Río Magdalena, ; less commonly ) is the main river of Colombia, flowing northward about through the western half of the country. It takes its name from the biblical figure Mary Magdalene. It is navigable through much o ...
in
Colombia, the upper
Columbia River
The Columbia River ( Upper Chinook: ' or '; Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, ...
in
British Columbia, Canada, the
Drumheller Channels of the
Channeled Scablands
The Channeled Scablands are a relatively barren and soil-free region of interconnected relict and dry flood channels, coulees and cataracts eroded into Palouse loess and the typically flat-lying basalt flows that remain after cataclysmic floods ...
of the state of Washington, USA, and the upper
Narew River
The Narew (; be, Нараў, translit=Naraŭ; or ; Sudovian: ''Naura''; Old German: ''Nare''; uk, Нарва, translit=Narva) is a 499-kilometre (310 mi) river primarily in north-eastern Poland, which is also a tributary of the river Vis ...
in
Poland
Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...
. The term
anabranch
An anabranch is a section of a river or stream that diverts from the main channel or stem of the watercourse and rejoins the main stem downstream. Local anabranches can be the result of small islands in the watercourse. In larger anabranches, t ...
has been used for segments of anastamosing rivers.
In cave systems anastomosis is the splitting of cave passages that later reconnect.
References
{{reflist
Angiology
Digestive system
Evolutionary biology
Petrology concepts
Surgery