Pseudopod
Pseudopods or
pseudopodia (false feet) are temporary projections of
eukaryotic cells. Cells having this faculty are generally referred to as
amoeboids.
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 act in polymerization is at the origin of the force propelling the cell forwards.
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 by
phagocytosis. Phagocytosis pseudopods have arisen in a number of different
protist groups, but also in some cells (
phagocytes) in
multicellular organisms.
Pseudopods can be classified into several varieties according to their appearance:
Lobopodia are bulbous, short and blunt in form, very typical of
Amoebozoa.
Filopodia 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.
