filopodium GO:0030028 cellular_component NIF_Subcellular:sao1046371754 A filopodium may be approximately 0.1 um wide, 5-10 um long, and up to 50 um long in axon growth cones; contain a loose bundle of about 20 actin filaments oriented with their plus ends pointing outward. Note that filopodia on dendritic shafts are distinct from other types of filopodia (even those found in dendritic growth cones) and may react differently to stimuli, as shown in PMID:12904473. GO:0030175 Wikipedia:Filopodia Thin, stiff, actin-based protrusion extended by the leading edge of a motile cell such as a crawling fibroblast or amoeba, or an axonal or dendritic growth cone, or a dendritic shaft. actin-based cell projection