Pseudopodia

Pseudopods ( pseudopodia, singular: pseudopodium ) are cytoplasmic eukaryotic cells. In protists, they are morphologically very diverse and fulfill numerous functions especially in movement and metabolism.

Forms of pseudopodia

Essentially, five types can be distinguished from pseudopodia: Lobopodien, filopodia, lamellipodia, and Retikulopodien Axopodien.

Lobopodien

Lobopodien are found especially in Amoebozoa. They taper to a point or tubes, tongue- or finger- shaped, and can change their shape very quickly. In its interior, the plasma flows very quickly. They are used either individually ( monopodial species) or in larger numbers ( polypodiale species) formed. Lobopodien serve in particular the movement.

Filopodia

Filopodia, see, inter alia, to with radiolarians ( Radiolaria ) and are thread- like protrusions of the cell, straight, sometimes bent usually, sometimes weakly branched. An axoneme of microtubules missing. In macrophage filopodia act as tentacles pull the bound objects to the cell in order to annex by phagocytosis.

Lamellipodia

Lamellipodia are very shallow and broad cell processes, for example, to find some Aconchulina.

Retikulopodien

Retikulopodien are special forms of pseudopodia, which are found exclusively as single-celled organisms with predominantly stationary lifestyle in foraminifera.

The pseudopods branch out and can again merge. So they form extensive networks ( pseudopodiale networks ) that serve the prey, locomotion, transport of organelles within the cell and anchored in the substrate. Retikulopodien are always true to grain flow and inner microtubules.

Axopodien

Axopodien, sometimes also called Actinopodien, found, inter alia with heliozoan and radiolarians and are particularly long and straight cell processes with an axoneme of microtubules. They are used in addition to the capture of prey of increasing the water resistance to slow a fall and locomotion.

Cellular processes involved in the formation of pseudopodia

The example of the amoeba cellular processes will be emphasized: amoebas possess an outer hyaline ectoplasm, which is present in the gel state, and an inner granular endoplasm, which is present in the sol state. In the boundary layer between endoplasm and ectoplasm are actin and myosin filaments whose stringing sliding and stick similar to the contraction and slackening of muscle cells to a stiffness of the affected area leads. A Actinbindungsprotein ( ABP) linked actin into a gel-like network. Now the calcium content increases, as gelsolin is free, which decomposes the actin filaments, this has the consequence that the ectoplasm passes into the effective region of the gelsolin in the sol state vanishes ( physical state change). The actin -myosin interaction is dissolved at the location. At the opposite end, the physiological end ( Uroid ) of the cell, and this interaction remains contracted. Thus, the endoplasm is displaced and flows to the front, where no ectoplasm, so no gel-like shell is gone. The endoplasm can therefore happen in this area, the actin -myosin network, but not the granular inclusions and cell organelles. This flow of plasma leads to the retraction of the pseudopodia Uroid, This leads to wrinkling of the cell membrane and the formation of new pseudopodia by the front end protrusion of the cell membrane. The pseudopodia disappear again when the ABP establishes the actin filaments again.

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