lamellipods

Lamellipods are broad, flattened, sheet-like extensions of the cell membrane that are characteristic of motile animal cells, particularly fibroblasts and some types of protozoa. They are dynamic structures that play a crucial role in cell migration, adhesion, and sensing the environment. These structures are formed by the rapid polymerization of actin filaments at the leading edge of the cell. The actin network within the lamellipod is highly branched and mesh-like, driven by proteins such as Arp2/3 complex.

The formation and retraction of lamellipods are tightly regulated processes involving signaling pathways that respond to cues from the extracellular environment, such as growth factors or cell-to-cell contact. Lamellipods are essential for various biological processes, including wound healing, immune surveillance, embryonic development, and metastasis of cancer cells. Their ability to explore and adhere to the substrate allows cells to move directionally across surfaces. The leading edge of a lamellipod is often characterized by a thin, ruffled membrane where new membrane and cytoskeletal material are continuously added. In contrast, the trailing edge of the cell retracts, allowing for forward movement. The dynamic nature of lamellipods enables cells to adapt to changing surroundings and perform complex migratory behaviors.