Pseudopod.html

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Pseudopods or pseudopodia(singular pseudopodium) (from the Greek word ψευδοπόδια, ψευδός "fake, false" + πόδια "feet") are temporary projections of eukaryotic cells. Cells having 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. This is how amoebas move, as well as some cells found in animals, such as white blood cells.

Reproduction

First and foremost, the cell surface extends a membrane process, termed a lamellipodium. Polymerization of actin takes place and form filaments at the leading edge, which subsequently will blend into one another to form networks. It is supposed that actin polymerization is at the origin of the force propelling the cell forwards.

Function

Mechanical role

Pseudopods are one of the three locomotion modes of unicellular organisms (together with flagella and cilia).

Pseudopods are also important in cell signaling, angiogenesis and phagocytosis.

Morphology

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

• Lobopodia are bulbous, short and blunt in form, very typical of Amoebozoa.

• Filopodia are more slender and filiform with pointed ends, consisting mainly of ectoplasm. These formations are supported by microfilaments.

• Reticulopodia, also known as reticulose pseudopods, are complex formations where individual pseudopods are blended together and form irregular nets.

• Axopodia 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 or further research needed] takes a strain on the helix for after the sensory action has occurred, it then later on dies.

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