"Projection at the leading edge of a crawling cell; the protrusions are supported by a microfilament meshwork [goid 1726] [pmid 9852149] [evidence IDA]; All of the contents of a cell excluding the plasma membrane and nucleus, but including other subcellular structures [goid 5737] [evidence IEA]; That part of the cytoplasm that does not contain membranous or particulate subcellular components [goid 5829] [pmid 9852149] [evidence IDA]; A filamentous structure formed of a two-stranded helical polymer of the protein actin and associated proteins. Actin filaments are a major component of the contractile apparatus of skeletal muscle and the microfilaments of the cytoskeleton of eukaryotic cells. The filaments, comprising polymerized globular actin molecules, appear as flexible structures with a diameter of 5-9 nm. They are organized into a variety of linear bundles, two-dimensional networks, and three dimensional gels. In the cytoskeleton they are most highly concentrated in the cortex of the cell just beneath the plasma membrane [goid 5884] [pmid 11598191] [evidence IDA]; The membrane surrounding a cell that separates the cell from its external environment. It consists of a phospholipid bilayer and associated proteins [goid 5886] [evidence IEA]; Thin cylindrical membrane-covered projections on the surface of an animal cell containing a core bundle of actin filaments. Present in especially large numbers on the absorptive surface of intestinal cells [goid 5902] [pmid 10793131] [evidence NAS]; The region of the plasma membrane located at the apical end of the cell [goid 16324] [evidence IEA]; Loosely bound to one surface of a membrane, but not integrated into the hydrophobic region [goid 19898] [pmid 7844168] [evidence IDA]; Thin, stiff protrusion extended by the leading edge of a motile cell such as a crawling fibroblast or amoeba, or an axonal growth cone; usually approximately 0.1 um wide, 5-10 um long, can be up to 50 um long in axon growth cones; contains a loose bundle of about 20 actin filaments oriented with their plus ends pointing outward [goid 30175] [pmid 12082081] [evidence IDA]; The portion of the cytoskeleton that lies just beneath the plasma membrane [goid 30863] [pmid 11598191] [evidence TAS]"