Pseudopod

Overview
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, 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.

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

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


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


 * Fillopodia 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 responsible for phagocytosis, by rapidly retracting in response to physical contacts. They are observed in radiolaria and heliozoa. This obviously takes a strain on the helix for after the sensory action has occurred, it then later on dies.