Pseudopod

Pseudopods or pseudopodia (false feet) are temporary projections of eukaryotic cells. Cells having this faculty are generally referred to as amoeboids.

Formation

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

Function

They are involved in a variety of cell activities, most notably:

Mechanical role

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

Sensory role

Pseudopods also capture prey phagocytosis. Phagocytosis pseudopods have arisen in a number of different protist groups, but also in some cells (phagocytes) in multicellular organisms.

Morphology

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

Lobopodia are bulbous, short and blunt in form, very typical of amoeba species.

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

Axopodia, observed mainly at radiolarians, are thin pseudopods contain complex arrays of microtubules and are enveloped by cytoplasm. Axopodia are responsible for phagocytosis, by rapidly retracting in response to physical contacts.

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