Lamellipodia are thin, sheet-like extensions of the cell membrane that play a crucial role in cell movement and shape. They are formed by the polymerization of actin filaments, which are proteins that provide structural support to cells. Lamellipodia help cells crawl along surfaces, allowing them to migrate during processes like wound healing and immune responses. These structures are particularly important in embryonic development and tissue repair, as they enable cells to explore their environment and interact with other cells. The dynamic nature of lamellipodia allows cells to rapidly change shape and direction, facilitating various biological functions.