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Vein skeleton of a Hydrangea leaf showing anastomoses of veins

An anastomosis (/əˌnæstəˈmoʊsɪs/, 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 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 is called a reanastomosis. Anastomoses that are abnormal, whether congenital or acquired, are often called fistulas.

The term is used in medicine,[1] biology, mycology, geology, and geography.

Etymology

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Anastomosis: medical or Modern Latin, from Greek ἀναστόμωσις, anastomosis, "outlet, opening", Greek ana- "up, on, upon", stoma "mouth", "to furnish with a mouth".[2] Thus the -stom- syllable is cognate with that of stoma in botany or stoma in medicine.

Medical anatomy

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A network of blood vessels

An anastomosis is the connection of two normally divergent structures.[3] It refers to connections between blood vessels or between other tubular structures such as loops of intestine.

Circulatory

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In circulatory anastomoses, many arteries naturally anastomose with each other; for example, the inferior epigastric artery and superior epigastric artery, or 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 a large blood supply, thus helping regulate systemic blood flow.[citation needed]

Surgical

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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,[4] hand sewn anastomosis,[4] end-to-end anastomosis (EEA).[5] Anastomosis can be performed by hand or with an anastomosis assist device.[6] Studies have been performed comparing various anastomosis approaches taking into account surgical "time and cost, postoperative anastomotic bleeding, leakage, and stricture".[7]

Anastomotic leakage in colorectal cancer surgery

Failure of an intestinal anastomosis with leakage of intestinal content in to the abdominal cavity is one of the most severe complications after bowel surgery. The severity of anastomotic leakage varies ranging from mild with minimal impact on the patient to severe and potentially fatal, with negative impact on both short- and long-term outcomes. The incidence has not changed in recent decades, despite improvement in surgical techniques, prehabilitation and perioperative care. Anastomotic leakage after rectal cancer surgery is higher and documented to occur in 9-11%, after colon resection the incidence of leakage is lower and about 6%.[8][9] Systemic factors contributing to anastomotic failure include sepsis, anemia, diabetes mellitus, previous irradiation, malnutrition, steroid use, smoking, heavy alcohol consumption, obesity and certain disease conditions like Chron's disease.[10][11]

Signs of an anastomotic leak include fever, abdominal pain or peritonitis, leukocytosis and tachycardia or new-onset arrythmias. Anastomotic leakage is usually diagnosed 5-8 days post-surgery.[11] A CT scan with pneumoperitoneum and significant free fluid or inflammatory changes around the anastomosis are suggestive of an anastomotic failure. Depending on the magnitude of the defect and leak different treatments are indicated. A localized anastomotic leak without systemic sepsis or peritonitis can be managed with antibiotics and if possible, drainage of the abscess. Anastomotic leaks associated with peritonitis or systemic sepsis requires an operation with either revision of the anastomosis if feasible or fecal diversion proximally or at the site of the anastomosis with a stoma.[10]

Pathological

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Pathological anastomosis results from trauma or disease and may involve veins, arteries, or intestines. These are usually referred to as fistulas. 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 (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 the liver in patients with portal hypertension, often resulting in hemorrhoids, esophageal varices, or caput medusae.[citation needed]

Biology

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Evolution

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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 the case of recent research that shows that ancestral populations along human and chimpanzee lineages may have interbred after an initial branching event.[12] The concept of anastomosis also applies to the theory of symbiogenesis, in which new species emerge from the formation of novel symbiotic relationships.[citation needed]

Mycology

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Anastomosing gills of Marasmius cf. cladophyllus

In mycology, anastomosis is the fusion between branches of the same or different hyphae.[13] Hence 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 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.[14]

For fungi, anastomosis is also a component of reproduction. In some fungi, two different haploid 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 and meiosis to complete the sexual cycle.[citation needed]

Also the term "anastomosing" is used for mushroom gills which interlink and separate to form a network.[15]

Botany

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Main article: Inosculation

The growth of a strangler fig around a host tree, with tendrils fusing together to form a mesh, is called anastomosing.[16]

Geosciences

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Geology

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In geology, veins of quartz (or other) minerals can display anastomosis.[17]

Ductile shear zones frequently show anastomosing geometries of highly-strained rocks around lozenges of less-deformed material.[18]

Molten lava flows sometimes flow in anastomosed lava channels[19] or lava tubes.[20]

In cave systems, anastomosis is the splitting of cave passages that later reconnect.[21]

Geography and hydrology

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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,[22] again in contrast with braided rivers.

Rivers with anastomosed reaches include the Magdalena River in Colombia,[23] the upper Columbia River in British Columbia, Canada,[24] the Drumheller Channels of the Channeled Scablands of the state of Washington, US, and the upper Narew River in Poland.[25] The term anabranch has been used for segments of anastomosing rivers.

Braided streams show anastomosing channels around channel bars of alluvium.[26]

References

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Anastomosis

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Anastomosis refers to a connection or opening between two normally separate structures, such as blood vessels, , or tubular organs like the intestines, enabling the flow of fluids, blood, or signals between them. These connections can occur naturally in biological systems or be surgically created to restore function or bypass obstructions. The term is also used in and to describe interconnected multiple-channel river systems known as anastomosing rivers. In biology, natural anastomoses are prevalent in the , where they provide alternative pathways for flow to maintain organ during blockages or narrowing. Notable examples include the Circle of Willis at the base of the , formed by communicating arteries from the internal carotid and vertebral systems, which ensures continuous cerebral supply, and venous anastomoses in superficial veins like the great saphenous, which help sustain circulation if a vessel is compromised. Beyond vasculature, natural anastomoses appear in neural structures, such as extracranial-intracranial connections, and even in fungi, where hyphal fusion facilitates gene exchange across 14 anastomosis groups. Physiologically, these natural junctions enhance redundancy and resilience, as seen in the formation of the dorsal aorta through vessel fusion in mammalian development. Surgical anastomosis, a cornerstone of modern medicine, involves deliberately joining structures to repair defects, reconnect tissues after resection, or create access for treatments like dialysis. Common types include vascular (e.g., coronary bypass grafting to reroute blood around blockages), intestinal (e.g., ileocolic reconnection after bowel tumor removal), and arteriovenous fistulas for . Techniques vary, such as end-to-end (joining open ends with sutures), side-to-side (stapling sides to minimize narrowing), and end-to-side (attaching a smaller vessel's end to a larger one's side). follows a biological process involving , proliferation with deposition and driven by factors like VEGF and TGF-β, and remodeling to achieve tensile strength, though the colon heals more slowly than the small bowel due to and collagenase influences. Risks include leakage (1-6% in intestinal cases), , , and stricture formation, underscoring the need for precise technique in procedures like or .

General Concept

Definition and Classification

Anastomosis refers to the union or of two structures, such as vessels, channels, or passages, that are typically separate, enabling direct communication or flow between them. This applies broadly in and related fields, where it describes the merging of branching networks into a continuous system. For instance, in schematic representations, an anastomosis may appear as a reconnection of diverging branches, such as in a Y-shaped configuration where two channels diverge and then join downstream, facilitating alternative pathways. Anastomoses are classified into natural (physiological) and artificial types, with the latter encompassing both surgical creations and pathological formations. anastomoses occur inherently in biological systems, providing or connectivity without intervention. Artificial anastomoses, by contrast, are deliberately formed during surgery to restore function or are abnormal connections arising from processes, such as unintended vessel linkages due to or . Within vascular contexts, basic types of anastomoses include arterial-arterial (connecting two arteries), venous-venous (linking two veins), and arteriovenous (joining an artery to a vein). These can further be categorized by configuration: end-to-end (joining the open ends of two structures to form a continuous tube), side-to-side (connecting the sides of two structures for bidirectional flow), and end-to-side (attaching the end of one structure to the side of another). Anastomoses manifest across scales, from microscopic cellular levels—such as endothelial cell connections during vascular development—to macroscopic features like river channel confluences in . In human , circulatory examples include arterial networks that ensure flow continuity.

Etymology and Historical Development

The term "anastomosis" originates from Ancient Greek ἀναστόμωσις (anastómōsis), meaning "providing a mouth or outlet," derived from the prefix ana- ("again" or "up") and stoma ("mouth"). This linguistic root reflects the concept of openings or connections, initially applied in medical contexts to describe intercommunications between tubular structures. The word entered English via medical Latin in the early 17th century, with the Oxford English Dictionary recording its first use in 1615 by anatomist Helkiah Crooke in a description of bodily vessels. In ancient medicine, the concept first appeared in the works of (c. 129–200 AD), the Roman physician who described invisible connections, or "anastomoses," between venous and arterial systems to explain blood flow, though he did not fully grasp systemic circulation. This idea persisted into the , where anatomist (1514–1564) built upon Galen's framework in his seminal De humani corporis fabrica (1543), noting circulatory links between vessels while challenging some Galenic assumptions about their primacy in blood distribution.02229-0/fulltext) By the 17th century, (1578–1657) advanced the understanding in Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus (1628), postulating the existence of capillary-level anastomoses between arteries and veins as essential to closed circulation, a later confirmed microscopically. During the , the term expanded beyond into natural sciences, with 1800s naturalists applying it to describe branching interconnections in , such as networks in leaves, and in to characterize patterns where channels rejoin to form stable islands. James Jackson introduced "ana-branches" in 1834 as a term for anastomosing channels, influencing hydrological . By the early , the concept gained standardization in , where it denoted the fusion of fungal hyphae to form reticulate networks, a process critical to mycelial growth and observed in studies of species like arbuscular mycorrhizal fungi. This broadening reflected the term's versatility across disciplines, rooted in its original anatomical significance.

Medical Anatomy

Circulatory Anastomoses

Circulatory anastomoses refer to natural interconnections between arteries, veins, or capillaries in the cardiovascular system, forming alternative pathways that ensure continuous blood flow and tissue perfusion even if a primary vessel is compromised. These connections are integral to the vascular architecture, allowing redundancy in circulation to maintain organ function under varying physiological conditions. They are classified into functional and potential types based on their openness and activity. Functional anastomoses remain open under normal conditions, facilitating constant blood exchange, as seen in the palmar arches of the hand where the radial and ulnar arteries interconnect to supply the digits. In contrast, potential anastomoses are typically closed or minimal in diameter but can dilate during increased demand or occlusion, such as the circle of Willis at the base of the brain, which links the major to redistribute flow. Anatomically, circulatory anastomoses are distinguished as extrinsic or intrinsic. Extrinsic anastomoses occur between major vessels from different arterial sources, providing broad collateral networks, while intrinsic anastomoses form within specific organs or tissues, such as the sinusoids in the liver where hepatic arterial and portal venous blood mix directly in capillary-like channels. Key examples include coronary collaterals, which interconnect epicardial arteries to prevent myocardial ischemia during reduced flow; the retinal vascular network, where arteriolar branches link to ensure optic tissue oxygenation; and gastrointestinal arcades in the mesenteric circulation, which interconnect branches of the superior and inferior mesenteric arteries for intestinal . These structures play critical roles in physiological , particularly through collateral circulation that mitigates ischemia by rerouting to deprived areas, as in the coronary where pre-existing networks can sustain myocardium during arterial narrowing. Additionally, arteriovenous anastomoses in the skin, such as those in the fingers and toes, contribute to by shunting to the surface for heat dissipation or conserving core temperature via in response to environmental changes.

Surgical Anastomoses

Surgical anastomosis involves the deliberate creation of a connection between two tubular structures, such as segments of the intestine or blood vessels, to restore functional continuity following resection or to pathological obstructions. This procedure approximates the lumens of the structures to promote through tissue , allowing the natural processes of , proliferation, and remodeling to form a stable union. The success of an anastomosis depends on factors like adequate blood supply, minimal tension, and precise alignment to prevent dehiscence or ischemia. Common techniques for performing surgical anastomoses include hand-sewn methods, which utilize interrupted or continuous sutures to approximate tissues, and stapled approaches that employ circular or linear stapling devices for faster execution in accessible sites. Mechanical couplers, such as vascular rings or clips, offer sutureless alternatives in microvascular surgery by compressing vessel walls to achieve hemostasis and patency. Anastomotic configurations vary by anatomical needs: end-to-end joins reconnect collinear segments, side-to-side creates parallel lumens for wider flow, and end-to-side facilitates branching connections, as seen in arterial bypasses. These methods are selected based on the site's accessibility, tissue thickness, and surgeon expertise to optimize healing and minimize intraoperative time. Indications for surgical anastomosis span multiple specialties, including gastrointestinal resections for malignancies like , where ileocolic or colocolic joins restore bowel continuity post-tumor excision. In cardiovascular surgery, it is essential for coronary artery bypass grafting (CABG), connecting grafts to native vessels to reroute flow around occlusions. Organ transplantation relies on vascular pedicle anastomoses to reestablish arterial and venous connections, ensuring graft viability. These applications underscore the procedure's role in restoring physiological function while addressing underlying pathology. Despite advancements, complications remain a significant concern, with anastomotic leakage occurring in up to 10-15% of colorectal cases due to breakdown at the join site, leading to or . Stricture formation, resulting from excessive , can cause luminal narrowing and obstruction, while in vascular anastomoses risks graft failure from clot propagation. Key risk factors include excessive tension on the suture line, compromised vascularity from ischemia, and patient factors like or , which impair . Intraoperative strategies, such as perfusion assessment with fluorescence, help mitigate these risks. As of 2025, recent advances have enhanced precision and outcomes in surgical anastomoses. Robotic-assisted systems, notably the da Vinci platform, enable magnified visualization and tremor-filtered instrumentation, reducing error in complex vascular or intracorporeal bowel joins during minimally invasive procedures. Bioengineered grafts, incorporating biodegradable polymers seeded with endothelial cells, promote endothelialization and reduce thrombosis in small-diameter vessel replacements. Three-dimensional (3D)-printed patient-specific vascular models facilitate preoperative planning by simulating anastomotic sites, improving accuracy in transplants and endovascular repairs. Additionally, endovascular techniques using covered stents provide less invasive options for aortic or peripheral artery anastomoses, minimizing open surgery needs.

Pathological Anastomoses

Pathological anastomoses refer to aberrant vascular connections that develop due to underlying disease processes, bypassing normal circulatory pathways and leading to hemodynamic disruptions. Unlike physiological anastomoses, which provide , these abnormal links, such as arteriovenous fistulas (AVFs) or , arise from congenital defects or acquired conditions like trauma, , or neoplasia, often resulting in shunting of blood that impairs organ . These anomalies can originate congenitally, as seen in (PDA), where the fetal shunt between the and fails to close postnatally, creating a persistent low-resistance pathway that increases pulmonary blood flow and risks or . Acquired mechanisms include trauma-induced AVFs, where direct arterial-venous communications form from injury, or inflammatory processes like those in leading to enteroenteric fistulas; neoplastic causes involve tumor invasion creating vessel connections, while atherosclerotic changes promote collateral shunting. In , dilates pre-existing portosystemic anastomoses into shunts, such as gastroesophageal varices, diverting portal blood away from the liver and contributing to . Key examples illustrate the diverse manifestations and risks. Arteriovenous malformations (AVMs) in the or spine, often sporadic but sometimes hereditary as in (HHT), consist of tangled vessel networks lacking intervening capillaries, causing steal phenomena that deprive surrounding tissues of oxygen and leading to ischemia, seizures, or hemorrhage with a 2-4% annual rupture . In , coronary steal occurs when vasodilators open collateral anastomoses around stenoses, paradoxically reducing flow to ischemic myocardium and exacerbating . Portosystemic shunts in , like splenorenal collaterals, can cause life-threatening variceal bleeding or from unfiltered toxins entering systemic circulation. Clinically, these may present with symptoms such as bruits over pulsatile masses in AVFs, high-output heart failure from large shunts, or recurrent hemorrhages, potentially overwhelming normal circulatory redundancies. Diagnosis relies on imaging to visualize abnormal flow: digital subtraction angiography remains the gold standard for mapping shunts and planning interventions, while MRI and MR angiography provide non-invasive assessment of AVM nidus size, location, and associated ischemia without radiation exposure. Management strategies include endovascular embolization using coils or particles to occlude fistulas, achieving success rates over 80% in many AVFs, or surgical ligation for accessible lesions; for PDA, transcatheter closure is preferred in infants. In 2025, preclinical data on bispecific receptor-clustering antibodies for (HHT), driven by ENG or ACVRL1 mutations, demonstrate potential to restore ALK1-mediated signaling and prevent progression by targeting ALK1 and BMPRII receptors, potentially reducing the need for repeated embolizations.

Biological Contexts

Evolutionary Origins

Anastomoses have evolved as adaptive structures that enhance organismal resilience by forming redundant networks capable of maintaining flow continuity in the face of environmental variability, such as fluctuating or oxygen availability. In early multicellular organisms, these connections likely provided a selective advantage by distributing resources across interconnected cells, reducing to localized disruptions and promoting . This role is evident in the basal metazoan phylum Porifera (sponges), where anastomosing canal systems facilitate water circulation through a of interconnected chambers, marking one of the earliest phylogenetic appearances of such networks in animal evolution. Phylogenetically, anastomoses expanded during the period (approximately 419–359 million years ago) in vascular , with evidence from ancient ferns revealing anastomosing venation patterns in tissues that supported efficient and transport in terrestrial environments. In vertebrates, this development paralleled the evolution of gill arches in early , where vascular anastomoses in the afferent and efferent arteries created collateral pathways for blood flow, optimizing under dynamic aquatic conditions. These structures arose from modifications in primordial circulatory systems, transitioning from simple diffusion-based exchange in to pressurized networks in jawed vertebrates. The adaptive benefits of anastomoses are multifaceted across taxa: in , they prevent single-point failures in circulation, ensuring tissue perfusion during injury or occlusion, as seen in the redundant vascular loops of that buffer against hemodynamic stress. In fungi and , anastomoses facilitate resource sharing within colonial networks, enabling the redistribution of nutrients and genetic material to support colony-level resilience in heterogeneous soils. Fossil records, including Devonian fern fronds with interconnected vascular strands, provide direct evidence of these early adaptations, while genetic studies reveal homologs of (VEGF) in like cnidarians and nematodes, which regulate and tubulogenesis—precursors to involving anastomotic fusion. The conservation of genes underpinning anastomotic processes, such as VEGF signaling pathways, spans kingdoms from fungi to animals, highlighting a shared evolutionary toolkit for network formation that predates vascular specialization. This cross-kingdom preservation informs modern , where engineered anastomotic motifs draw on these ancient mechanisms to design resilient bioengineered tissues and microbial consortia for applications in and .

Fungal Anastomoses

In fungal biology, anastomosis refers to the fusion of hyphae, involving cytoplasmic continuity and often nuclear migration, which establishes interconnected mycelial networks essential for colony integrity and resource distribution. This process allows filamentous fungi to form cohesive structures that enhance survival in diverse environments by enabling the sharing of cellular contents across the network. Fungal anastomoses are classified into homokaryotic fusions, which occur between hyphae of the same genetic without triggering incompatibility responses, and heterokaryotic fusions, which involve genetically distinct strains and are frequently restricted by vegetative incompatibility mechanisms to prevent deleterious gene combinations. Additionally, they can be vegetative, facilitating asexual network expansion during colony growth, or sexual, contributing to in compatible strains under specific conditions. These distinctions influence the extent of genetic exchange and network stability within fungal populations. The mechanisms of hyphal anastomosis proceed through three phases: pre-contact homing directed by chemotropic signals, post-contact adhesion and dissolution mediated by lytic enzymes such as chitinases and glucanases that degrade and β-1,3-glucan components, and post-fusion plasma membrane merger allowing cytoplasmic and nuclear mixing. Compatibility is regulated by mating-type genes in loci, which encode transcription factors that either permit fusion in matching strains or activate in incompatible heterokaryotic encounters to safeguard against viral transmission or genetic instability. Glycosyltransferases like GT69-2 further support remodeling during dissolution, ensuring stable pore formation for fusion. Ecologically, fungal anastomoses play a pivotal role in sharing across mycelial , allowing translocation of water, minerals, and to optimize in nutrient-poor soils. They confer resistance to by enabling collective defense responses, such as the distribution of compounds, and underpin mycorrhizal symbioses where fungi connect in common , enhancing host growth and stress tolerance through bidirectional exchange. These foster resilience by linking communities and facilitating interspecies interactions. Recent 2025 research on dark septate endophytes like demonstrates how anastomotic networks form "common fungal networks" that enable signaling and resource transfer between plants, mimicking internet-like connectivity for water and nutrient movement across air gaps, with significant increases in receiver plant . Such findings highlight anastomoses' role in non-mycorrhizal fungal symbioses, analogous to early evolutionary adaptations that allowed fungi to exploit terrestrial niches through networked growth.

Plant Anastomoses

In plants, anastomosis refers to the natural fusion or interconnection of vascular tissues, such as and vessels, or between and stems, occurring either within a single individual or between adjacent of the same . These connections form through the physical merging of cell walls and the alignment of conductive elements, enabling the seamless flow of water, nutrients, and photosynthates across the joined structures. Key types of plant anastomoses include root grafting, where adjacent tree roots fuse to create shared vascular networks, as observed in species like balsam fir (Abies balsamea) and quaking aspen (Populus tremuloides). Another type involves vascular anastomoses in stems, often mediated by the vascular cambium, which produces regenerative sieve tubes in phloem that bridge bundles, particularly in internodes of plants like Cucurbita species. These stem connections typically arise post-wounding or during secondary growth, restoring continuity in the vascular system. The development of anastomoses is regulated by hormonal signals, particularly gradients that promote and vascular reconnection at fusion sites. At the cellular level, plasmodesmata—cytoplasmic channels spanning cell walls—facilitate symplastic transport of signaling molecules and nutrients, enabling integration between fused tissues even across compatible grafts. This process begins with formation at contact points, followed by precise alignment of vascular elements under influence. Functionally, anastomoses support in ecosystems by allowing carbon and sharing among connected individuals, often enhanced by ectomycorrhizal fungal symbioses that link grafts for belowground transfer. They also provide mechanical stability, reducing uprooting risk during windstorms, as evidenced in boreal (Pinus banksiana) stands where grafted roots distribute mechanical loads. Notable examples include self-anastomosis in English ivy (), where climbing stems interconnect to form extensive networks that enhance structural support and resource flow. In clonal colonies like the Pando quaking aspen grove in , natural root grafts connect thousands of ramets into a single genetic entity spanning over 43 hectares, facilitating collective resource management.

Animal Anastomoses

In animal physiology, anastomoses refer to natural interconnections between structures such as blood vessels, nerves, or tracheal tubes, facilitating the exchange of oxygen, nutrients, or signals across diverse phyla including and vertebrates. These connections enhance system redundancy and adaptability, differing markedly between open circulatory systems typical of like arthropods, where flows freely through sinuses and anastomoses provide direct tissue , and closed systems in vertebrates, where blood remains confined to vessels with more intricate anastomotic networks for precise regulation. Representative examples illustrate this diversity. In insects, such as , tracheal anastomoses form a branched network of epithelial tubules that deliver oxygen directly to tissues, with interconnections ensuring efficient even under varying metabolic demands. In fish gill arches, like those of teleosts, vascular anastomoses within the arterioarterial pathway connect afferent and efferent filaments, supporting respiratory gas transfer while interlamellar shunts regulate flow. Among non-human mammals, collateral anastomoses in the lungs and heart, as observed in species like dogs and pigs, provide alternative pathways that maintain during localized occlusion, with coronary collaterals varying widely across mammalian taxa to buffer ischemic stress. These structures serve critical functions, particularly in adaptive responses to injury or environmental challenges. In earthworms (Lumbricus terrestris), nerve anastomoses enable segment regeneration by reconnecting medial and lateral giant fibers, restoring escape reflex pathways within days through targeted axonal sprouting. Amphibians, such as frogs (Rana spp.), utilize vascular shunts and anastomoses in their undivided hearts to redirect blood flow during hypoxic stress, minimizing pulmonary recirculation and prioritizing systemic oxygenation in aquatic or low-oxygen environments. Developmentally, anastomoses arise through angiogenesis driven by vascular endothelial growth factor (VEGF) signaling, a conserved mechanism in animal embryos where VEGF ligands induce endothelial sprouting and vessel fusion to form interconnected networks. In vertebrate embryos, such as zebrafish, VEGF gradients guide the anastomosis of intersegmental vessels, ensuring proper circulatory patterning. Comparative genomic analyses from 2020–2025 highlight conserved VEGF pathways across invertebrates and vertebrates, with orthologous genes in the PDGF/VEGF family, such as the Pvf genes in Drosophila and vegfa in mammals regulating anastomotic fusion via shared receptor tyrosine kinase signaling, underscoring evolutionary stability despite circulatory system complexity.

Geosciences

Geological Anastomoses

Geological anastomoses consist of interconnecting fault, , , or networks within rock masses, characterized by braided or ramifying patterns that link multiple pathways. These structures arise from the progressive linkage of individual fractures or veins, often enclosing host rock segments and creating complex, interconnected geometries. In , they represent a key manifestation of brittle deformation, where infiltration and fill the voids, stabilizing the network over time. The formation of geological anastomoses is driven primarily by tectonic stress, which induces fracturing, combined with mineralization processes that seal and reinforce the structures. For instance, under compressional or shear regimes, veins may develop anastomosing patterns within granitic host rocks as fluids carrying silica precipitate during episodic deformation events. This process is influenced by the rock's mechanical properties, fluid pressure, and temperature, leading to incremental growth through repeated crack-seal mechanisms. Syntectonic anastomoses form contemporaneously with deformation, actively participating in strain accommodation, whereas epigenetic types develop after the primary of the host rock, often during later tectonic phases or hydrothermal activity. These networks hold significant implications for resource exploration and geomechanical modeling. In ore deposit geology, anastomosing quartz vein systems serve as conduits for mineralizing fluids, hosting economic concentrations of metals like ; a prominent example occurs in the anastomosing quartz veins and shear zones of the Appalachian fold belts near Great Falls, , where native deposits have been documented. In , such fracture networks enhance or compartmentalize permeability, influencing fluid migration and trapping by providing preferential pathways while mineral sealing can reduce overall connectivity. Recent advancements in have improved the analysis of fracture networks in rocks. These structures also influence hydrological flow by channeling subsurface fluids through permeable zones in fractured aquifers.

Hydrological Anastomoses

Hydrological anastomoses refer to interconnected networks of channels and that split and rejoin, forming multiple, coexisting pathways on alluvial plains, distinct from single-thread dendritic drainage patterns. These systems, also known as anabranching or anastomosing rivers, feature stable channels separated by vegetated islands or bars, promoting a braided-like appearance but with greater permanence. Anastomosing river systems typically form in environments with high sediment loads, variable discharge regimes, and low-energy flow conditions, such as broad alluvial plains or subsiding basins. Avulsions—sudden shifts in channel position—play a key role in their development, allowing new channels to establish while older ones remain active, leading to a network of interconnected waterways. This contrasts with more dynamic systems influenced by high-gradient slopes or coarse sediments. Anastomosing rivers are distinguished from other multi-channel systems like braided rivers. Anastomosing types are characterized by multiple deep channels separated by cohesive, vegetated islands that resist frequent flooding and prevail in cohesive sediment environments with dense riparian vegetation, fostering long-term channel stability, whereas braided rivers exhibit unstable, shallow, shifting channels divided by non-vegetated gravel or sand bars prone to rapid reconfiguration and dominate in high-energy settings with abundant coarse material. Ecologically, these systems enhance biodiversity by creating diverse habitats for aquatic and terrestrial , while trapping that build fertile soils and mitigate downstream . They support nutrient cycling and in wetlands, with vegetated islands acting as buffers against floods and promoting in riparian zones. Recent 2025 climate models predict disruptions to anastomosed deltas, such as the River, where rising sea levels, reduced delivery from upstream dams, and intensified monsoons could accelerate and channel avulsions, threatening up to 54% of the delta with submergence by 2100 under an 80 cm sea-level rise scenario. Prominent examples include the in , an inland fan where avulsions sustain a complex anastomosing network amid subsiding tectonics, and the lower in , featuring gravel-bedded channels with stable vegetated divides that trap fine sediments. Restoration efforts for anastomoses, such as those in lowland European rivers, involve reconnecting channels to floodplains using low-gradient designs and remnant wetlands to revive multi-channel patterns, enhancing resilience to hydrological variability.

References

  1. https://my.clevelandclinic.org/health/treatments/24035-anastomosis
  2. https://www.sciencedirect.com/science/article/pii/S0012825200000386
  3. https://www.healthline.com/health/anastomosis
  4. https://guides.hostos.cuny.edu/bio140/6-28
  5. https://www.sciencedirect.com/topics/neuroscience/anastomosis
  6. https://www.verywellhealth.com/anastomosis-defined-3157034
  7. https://pmc.ncbi.nlm.nih.gov/articles/PMC9355065/
  8. https://www.merriam-webster.com/dictionary/anastomosis
  9. https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Anatomy_and_Physiology_%28Boundless%29/18%253A_Cardiovascular_System%253A_Blood_Vessels/18.2%253A_Arteries/18.2D%253A_Anastomoses
  10. https://pmc.ncbi.nlm.nih.gov/articles/PMC4515349/
  11. https://www.etymonline.com/word/anastomosis
  12. https://www.oed.com/dictionary/anastomosis_n
  13. https://pubmed.ncbi.nlm.nih.gov/24461486/
  14. https://pmc.ncbi.nlm.nih.gov/articles/PMC2776239/
  15. https://www.biologyonline.com/dictionary/anastomosis
  16. https://www.researchgate.net/publication/259682395_Multichannel_rivers_Their_definition_and_classification
  17. https://nph.onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2004.01236.x
  18. https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Anatomy_and_Physiology_(Boundless)/18:_Cardiovascular_System:_Blood_Vessels/18.2:_Arteries/18.2D:_Anastomoses
  19. https://pmc.ncbi.nlm.nih.gov/articles/PMC4140974/
  20. https://pmc.ncbi.nlm.nih.gov/articles/PMC6696371/
  21. https://www.ncbi.nlm.nih.gov/books/NBK53073/
  22. https://bmcmedicine.biomedcentral.com/articles/10.1186/1741-7015-11-143
  23. https://pmc.ncbi.nlm.nih.gov/articles/PMC4861183/
  24. https://pmc.ncbi.nlm.nih.gov/articles/PMC4882170/
  25. https://pmc.ncbi.nlm.nih.gov/articles/PMC3536859/
  26. https://pmc.ncbi.nlm.nih.gov/articles/PMC8610634/
  27. https://pmc.ncbi.nlm.nih.gov/articles/PMC10643590/
  28. https://pmc.ncbi.nlm.nih.gov/articles/PMC9794342/
  29. https://pmc.ncbi.nlm.nih.gov/articles/PMC6430759/
  30. https://pmc.ncbi.nlm.nih.gov/articles/PMC12369093/
  31. https://pmc.ncbi.nlm.nih.gov/articles/PMC12513347/
  32. https://pubs.aip.org/pof/article/37/10/101301/3366753/Recent-advances-in-the-fabrication-of-vascularized
  33. https://www.mdpi.com/2075-4418/14/15/1658
  34. https://www.ncbi.nlm.nih.gov/books/NBK559213/
  35. https://radiopaedia.org/articles/portosystemic-collateral-pathways-1?lang=us
  36. https://rarediseases.org/rare-diseases/arteriovenous-malformation/
  37. https://pmc.ncbi.nlm.nih.gov/articles/PMC3968593/
  38. https://journals.sagepub.com/doi/10.1177/1756284820961287
  39. https://www.biospace.com/press-releases/diagonal-therapeutics-to-present-new-preclinical-data-demonstrating-disease-modifying-potential-of-receptor-clustering-antibody-approach-in-hht-at-eha-2025-congress
  40. https://journals.biologists.com/jcs/article/s2-32/125/1/62152/Studies-on-the-Comparative-Anatomy-of-Sponges-III
  41. https://pmc.ncbi.nlm.nih.gov/articles/PMC7755389/
  42. https://academic.oup.com/aob/article-pdf/87/5/553/7984442/870553.pdf
  43. https://www.pnas.org/doi/10.1073/pnas.0810959106
  44. https://pmc.ncbi.nlm.nih.gov/articles/PMC551528/
  45. https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2013.00345/full
  46. https://academic.oup.com/femsec/article/88/3/437/584938
  47. https://www.ncbi.nlm.nih.gov/books/NBK5993/
  48. https://pmc.ncbi.nlm.nih.gov/articles/PMC7477884/
  49. https://pmc.ncbi.nlm.nih.gov/articles/PMC8092235/
  50. https://pmc.ncbi.nlm.nih.gov/articles/PMC6132195/
  51. https://www.nature.com/articles/s42003-025-08432-x
  52. https://www.sciencedirect.com/science/article/abs/pii/S0378112720311579
  53. https://link.springer.com/article/10.1007/BF00262647
  54. https://pubmed.ncbi.nlm.nih.gov/28321670/
  55. https://pmc.ncbi.nlm.nih.gov/articles/PMC5762790/
  56. https://pmc.ncbi.nlm.nih.gov/articles/PMC5350079/
  57. https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2014.00727/full
  58. https://pmc.ncbi.nlm.nih.gov/articles/PMC9039061/
  59. https://link.springer.com/article/10.1007/s00468-025-02624-y
  60. https://www.research-collection.ethz.ch/bitstreams/556ab8d3-5643-415c-99c9-bbd489a837e9/download
  61. https://www.researchgate.net/publication/51180129_Molecular_and_dendrochronological_analysis_of_natural_root_grafting_in_Populus_tremuloides_Salicaceae
  62. https://organismalbio.biosci.gatech.edu/nutrition-transport-and-homeostasis/animal-circulatory-systems/
  63. https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Map%253A_Raven_Biology_12th_Edition/48%253A_The_Circulatory_System/48.01%253A_Invertebrate_Circulatory_Systems
  64. https://pmc.ncbi.nlm.nih.gov/articles/PMC5972413/
  65. https://pubmed.ncbi.nlm.nih.gov/12115898/
  66. https://pubmed.ncbi.nlm.nih.gov/3440266/
  67. https://academic.oup.com/icb/article-pdf/28/4/1077/396089/28-4-1077.pdf
  68. https://onlinelibrary.wiley.com/doi/am-pdf/10.1111/brv.12572
  69. https://www.cell.com/cell/fulltext/S0092-8674(02)00676-1
  70. https://pmc.ncbi.nlm.nih.gov/articles/PMC12091601/
  71. https://www.nature.com/articles/s41392-025-02249-0
  72. https://www.researchgate.net/publication/308165914_Glossary_of_fault_and_other_fracture_networks
  73. https://www.sciencedirect.com/science/article/abs/pii/S0191814109000765
  74. https://www.researchgate.net/publication/234164081_A_review_of_the_formation_of_tectonic_veins_and_their_microstructures
  75. https://www.911metallurgist.com/blog/mineral-vein-formation-mechanism/
  76. https://www.linkedin.com/pulse/determining-structural-ages-veins-brett-davis
  77. https://pubs.usgs.gov/publication/b1286
  78. https://npshistory.com/publications/geology/bul/1286.pdf
  79. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014JB011520
  80. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023JH000103
  81. https://www.sciencedirect.com/science/article/abs/pii/S0012825200000386
  82. https://www.researchgate.net/publication/222888248_Anastomosing_rivers_A_review_of_their_classification_origin_and_sedimentary_products
  83. https://www.geogsci.com/EN/10.1007/s11442-019-1598-x
  84. https://wildearthlab.com/2023/04/12/channel-types/
  85. https://phys.org/news/2025-07-drivers-global-river-delta-scientists.html
  86. https://www.lemonde.fr/en/environment/article/2025/11/01/water-rises-and-land-sinks-in-vietnam-s-mekong-delta_6746986_114.html
  87. https://www.researchgate.net/publication/238379179_Avulsion_and_anastomosis_in_the_panhandle_region_of_the_Okavango_Fan_Botswana
  88. https://wiki.reformrivers.eu/images/4/48/Fact_sheet-_Large_anastomosing_lowland_rivers.pdf
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