The myofibril assembly process that results in the organization of muscle actomyosin into sarcomeres. The sarcomere is the repeating unit of a myofibril in a muscle cell, composed of an array of overlapping thick and thin filaments between two adjacent Z discs.

The process whose specific outcome is the progression of the skeletal muscle fiber over time, from its formation to the mature structure. Muscle fibers are formed by the maturation of myotubes. They can be classed as slow, intermediate/fast or fast.

A contractile actin filament bundle that consists of short actin filaments with alternating polarity, cross-linked by alpha-actinin and possibly other actin bundling proteins, and with myosin present in a periodic distribution along the fiber.

A cell-cell adherens junction which forms a continuous belt near the apex of epithelial cells.

An occluding cell-cell junction that is composed of a branching network of sealing strands that completely encircles the apical end of each cell in an epithelial sheet; the outer leaflets of the two interacting plasma membranes are seen to be tightly apposed where sealing strands are present. Each sealing strand is composed of a long row of transmembrane adhesion proteins embedded in each of the two interacting plasma membranes.

Small region on the surface of a cell that anchors the cell to the extracellular matrix and that forms a point of termination of actin filaments.

The portion of the plasma membrane at the lateral side of the cell. In epithelial cells, lateral plasma membranes are on the sides of cells which lie at the interface of adjacent cells.

A thin sheetlike process extended by the leading edge of a migrating cell or extending cell process; contains a dense meshwork of actin filaments.

Electron-dense region associated with a smooth muscle contractile fiber.

The area of a motile cell closest to the direction of movement.

The outer membrane of a muscle cell, consisting of the plasma membrane, a covering basement membrane (about 100 nm thick and sometimes common to more than one fiber), and the associated loose network of collagen fibers.

The desmosomal part containing plakoglobins, plakophilins, the N-termini of desmoplakins, as well as the cytoplasmic tails of the desmosomal cadherins, which together attach the plaque to the plasma membrane.

The desmosomal part containing the C-termini of desmoplakins which interact with the keratin intermediate filaments, serving to tether the intermediate filaments to the plasma membrane.

An electron dense body which may contain granules.

An actin-rich cytoskeletal network located beneath the microvilli of the apical plasma membrane of polarized epithelial cells. In addition to actin filaments, the terminal web may contain actin-binding proteins, myosin motor proteins, and intermediate filaments. The terminal web can function as a contractile structure that influences the spatial distribution of microvilli as well as the development and morphogenesis of tissues containing polarized epithelial cells.