Reproduction
First, the cell surface extends a membrane process, a lamellipodium. Actin polymerizes, and, at its leading edge, the cell forms filaments that 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 forward. Pseudopodia (which translates to "false feet") are temporary cytoplasm-filled projections of the cell wall 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-Amoeba proteus) or a single pseudopodium may form on the surface of the body (monopodial-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 blend together. 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. Lobopodia are bulbous and amoebic. Filopodia are slender, sort of football shaped, 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.
Read more about this topic: Pseudopodia
Famous quotes containing the word reproduction:
“Although Samuel had a depraved imagination—perhaps even because of this—love, for him, was less a matter of the senses than of the intellect. It was, above all, admiration and appetite for beauty; he considered reproduction a flaw of love, and pregnancy a form of insanity. He wrote on one occasion: “Angels are hermaphrodite and sterile.””
—Charles Baudelaire (1821–1867)
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—Ludwig Wittgenstein (1889–1951)
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—Stephen Bayley (b. 1951)