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Figure 1. Lamellipodia are thin-like projections on the leading edge of a cell (Image A). It is a feature of motile cells such as endothelial cells, neurons, and immune cells. The lamellipodia on the leading edge of the cell (green arrows) contain ATP- bound actin and the lamella on the "spike" end of the cell contain ADP-bound actin (red arrow).
The difference between foot processes, and lamellipodia, which are broad sheet-like protrusions, and filopodia, which are long slender pointed extensions, is that lamellipodia and filopodia are especially significant for cell movement and migration, and they are "macro" membrane protrusions.
Lamella, in cell biology, is also used to describe the leading edge of a motile cell, of which the lamellipodia is the most forward portion. [5] The lipid bilayer core of biological membranes is also called lamellar phase. [6] Thus, each bilayer of multilamellar liposomes and wall of a unilamellar liposome is also referred to as a lamella.
The functions of pseudopodia include locomotion and ingestion: Pseudopodia are critical in sensing targets which can then be engulfed; the engulfing pseudopodia are called phagocytosis pseudopodia. A common example of this type of amoeboid cell is the macrophage. They are also essential to amoeboid-like locomotion.
Initially, small (0.25μm 2) focal adhesions called focal complexes (FXs) are formed at the leading edge of the cell in lamellipodia: they consist of integrin, and some of the adapter proteins, such as talin, paxillin and tensin. Many of these focal complexes fail to mature and are disassembled as the lamellipodia withdraw.
They are each about 1.5-2.5 μm in thickness. The anterior lamellae interweave more than posterior lamellae. The fibrils of each lamella are parallel with one another, but at different angles to those of adjacent lamellae. The lamellae are produced by keratocytes (corneal connective tissue cells), which occupy about 10% of the substantia propria.
The Arp2/3 complex appears to be important in a variety of specialized cell functions that involve the actin cytoskeleton. The complex is found in cellular regions characterized by dynamic actin filament activity: in macropinocytic cups, in the leading edge of motile cells (lamellipodia), and in motile actin patches in yeast. [14]
Scales may be piliform (hairlike) or flattened. The body or "blade" of a typical flattened scale consists of an upper and lower lamella with an air space in between. The surface towards the body is smooth and known as the inferior lamella. The upper surface, or superior lamella, has transverse and