Pseudopodia

: pseudopods or pseudopodia) is a temporary arm-like projection of a eukaryotic cell membrane that is emerged in the direction of movement.

Axopodia are the phagocytosis type with long, thin pseudopods supported by complex microtubule arrays enveloped with cytoplasm; they respond rapidly to physical contact.

The chemoattractants bind to G protein-coupled receptors, which activate GTPases of the Rho family (e.g. Cdc42, Rac) via G proteins.

The pseudopodium can then adhere to a surface via its adhesion proteins (e.g. integrins), and then pull the cell's body forward via contraction of an actin-myosin complex in the pseudopod.

This serves as a feedback loop to amplify and maintain the presence of local GTPase at the leading edge.

Y-shaped pseudopods are more frequent than de novo ones, which explain the preference of the cell to keep moving to the same direction.

[7] The functions of pseudopodia include locomotion and ingestion: Pseudopods can be classified into several varieties according to the number of projections (monopodia and polypodia), and according to their appearance.

These formations are supported by microfilaments which, unlike the filaments of lamellipodia with their net-like actin, form loose bundles by cross-linking.

Contrarily to other pseudopodia using the pressure exerted by actin polymerization on the membrane to extend, fibroblast lobopods use the nuclear piston mechanism consisting in pulling the nucleus via actomyosin contractility to push the cytoplasm that in turn push the membrane, leading to pseudopod formation.

To occur, this lobopodia-based fibroblast migration needs nesprin 3, integrins, RhoA, ROCK and myosin II.

Otherwise, lobopods are often accompanied with small lateral blebs forming along the side of the cell, probably due to the high intracellular pressure during lobopodia formation increasing the frequency of plasma membrane-cortex rupture.

These pseudopodia are primarily food-collecting structures, but also provide a means of hydrological transportation via the expansion of their surface areas.