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temporary outgrowth used by some microorganisms as an organ of feeding or locomotion (同)pseudopodium

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(アメーバの)仮足(移動・捕食の際一時的に出す舌状の突起物)

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/11/27 19:57:52」(JST)

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Pseudopods or pseudopodia (singular: pseudopodium) (from the Greek word ψευδοπόδια, ψευδός "false" + πόδια "feet") are temporary projections of eukaryotic cell membranes or unicellular protists. Cells that possess this faculty are generally referred to as amoeboids. Pseudopodia extend and contract by the reversible assembly of actin subunits into microfilaments. Filaments near the cell's end interact with myosin which causes contraction. The pseudopodium extends itself until the actin reassembles itself into a network.

It is supposed that actin polymerization is at the origin of the force propelling the cell forward.^{[citation needed]} Pseudopodia ("false foot") are temporary cytoplasm-filled projections of the cell membrane that certain eukaryotic cells use for motion or for ingesting nutrients. Most cells with this capability are referred to as amoeboids. Generally several pseudopodia arise from the surface of the body (polypodial, e.g. Amoeba proteus) or a single pseudopodium may form on the surface of the body (monopodial, e.g. Entamoeba histolytica).

Pseudopodia are formed by microtubule and filament structures. The cell surface projects a membrane process called the lamellipodium, which is supported inside by filaments that form at the leading edge, turning into networks as they merge. Cytoplasm flows into the lamellipodium, forming the pseudopodia.

The functions of pseudopodia include locomotion and the capturing of prey. Pseudopodia are critical in sensing prey that can then be engulfed; the engulfing pseudopodia are called phagocytosis pseudopodia. A common example of this sort of amoeboid cell is the human white blood cell.

Pseudopodia do not all look like amorphous blobs; instead, they can be classified by their distinct appearances.^[1] Lobopodia are bulbous and amoebic. Filopodia are slender, thread-like, and are supported largely by microfilaments. Reticulopodia are very complex and bear individual pseudopodia that form irregular nets. Axopodia are the phagocytosis type with long, thin pseudopods supported by complex, microtubule arrays enveloped with cytoplasm, and they respond rapidly to physical contact.

Morphology

Chaos carolinense, an amoeboid with Lobopodia

Pseudopods can be classified into several varieties according to their appearance:

Lobopodia are bulbous, short and blunt in form. They are very typical of Amoebozoa. These finger-like, tubular pseudopodia contain both ectoplasm and endoplasm.
Filopodia are more slender and filiform with pointed ends, consisting mainly of ectoplasm. These formations are supported by microfilaments. This is observed in Euglypha and Lecithium.
Reticulopodia,^[2] also known as reticulose pseudopods, are complex formations where individual pseudopods are blended together and form irregular nets. The primary function of reticulopodia, also known as myxopodia, is the ingestion of food, with locomotion a secondary function. Reticulopods are typical of Foraminifera.
Axopodia (also known as actinopodia) are thin pseudopods containing complex arrays of microtubules and are enveloped by cytoplasm. Axopodia are mostly responsible for phagocytosis by rapidly retracting in response to physical contacts. They are observed in radiolaria and heliozoa. This supposedly^{[citation needed]} takes a strain on the helix, for after the sensory action has occurred, it then later on dies. Principally, these pseudopodia are food collecting structures.

References

^ David J. Patterson (2000). "Amoebae: Protists Which Move and Feed Using Pseudopodia". Tree of Life Web Project. Retrieved September 2014.
^ http://www.eforams.icsr.agh.edu.pl/index.php/Reticulopodia

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English Journal

Quantitative Motion Analysis in Two and Three Dimensions.

Wessels DJ1, Lusche DF1, Kuhl S1, Scherer A1, Voss E1, Soll DR2.
Methods in molecular biology (Clifton, N.J.).Methods Mol Biol.2016;1365:265-92. doi: 10.1007/978-1-4939-3124-8_14.
This chapter describes 2D quantitative methods for motion analysis as well as 3D motion analysis and reconstruction methods. Emphasis is placed on the analysis of dynamic cell shape changes that occur through extension and retraction of force generating structures such as pseudopodia and lamellipodi
PMID 26498790

Modeling the Mechanosensitivity of Neutrophils Passing through a Narrow Channel.

Wu T1, Feng JJ2.
Biophysical journal.Biophys J.2015 Dec 1;109(11):2235-45. doi: 10.1016/j.bpj.2015.10.032.
Recent experiments have found that neutrophils may be activated after passing through microfluidic channels and filters. Mechanical deformation causes disassembly of the cytoskeleton and a sudden drop of the elastic modulus of the neutrophil. This fluidization is followed by either activation of the
PMID 26636935

Ultrastructural Changes of the Smooth Muscle in Esophageal Atresia.

Al-Shraim MM1, Eid RA1, Musalam AO1, Radad K1, Ibrahim AH2, Malki TA3.
Ultrastructural pathology.Ultrastruct Pathol.2015 Dec;39(6):413-8. doi: 10.3109/01913123.2015.1066913. Epub 2015 Aug 17.
Esophageal atresia (EA) with or without tracheo-esophageal fistula (TEF) is a relatively rare congenital anomaly. Despite the advances in the management techniques and neonatal intensive care, esophageal dysmotility remains a very common problem following EA/TEF repair. Our current study aimed to de
PMID 26548437

Japanese Journal

Chemotactic Amoeboid-like Shape Change of a Vesicle under a pH Gradient

Nawa Erika,Yamamoto Daigo,Shioi Akihisa
Bulletin of the Chemical Society of Japan advpub(0), 2015
… A vesicle that exhibited the extrusion and contraction of a pseudopod-like structure under a pH gradient was studied. … A pseudopod-like structure is extruded from the vesicle toward a pH gradient, created by NaOH diffusion, and is then contracted. …
NAID 130005093823

Development of Optical and Acoustic Hybrid Microscope for Visualization of a Single Cell

Shikama Joe,Sato Yu,Kobayashi Kazuto,Yoshida Koki,Nagaoka Ryo,Saijo Yoshifumi
生体医工学 52(Supplement), O-345-O-346, 2014
… As a result of imaging the 3T3-L1 mouse fibroblasts, good contrast was achieved in the portion of the cell nucleus and pseudopod in the acoustic image. …
NAID 130004948200

0118 円管内乱流パフの分裂(OS1 噴流,後流および剥離流れ現象の探求と技術革新,オーガナイズドセッション)

清水雅樹,マンネビルポール,ドゥゲヨハン,河原源太
流体工学部門講演会講演論文集 2012, 39-40, 2012-11-16
… A splitting puff first emits a kind of chaotic pseudopod made of azimuthally localized streaky structures at the downstream (leading) laminar-turbulent interface. …
NAID 110009951567