Lamellum

Lamellum is a term derived from the Latin lamella, meaning a small plate. In biology, it is used to describe a thin plate-like layer or subcellular region that appears in various tissues and contexts. Because the word is a descriptive label rather than a single established structure, its precise meaning can vary by field.

In cell biology, lamellum refers to a distinct zone located just behind the lamellipodium at the leading edge of migrating cells. The lamellum contains a network of actin filaments that is more bundled and less dynamic than the actin structure in the lamellipodium. It is associated with more stable focal adhesions and a slower turnover of adhesion components. The lamellum is thought to play a role in coordinating adhesion formation and disassembly, providing a transitional region that helps convert protrusive activity into forward movement. Its characteristics can differ among cell types, such as fibroblasts and keratocytes, and it is commonly studied using fluorescence imaging of actin and adhesion proteins.

Outside of cell migration, lamellum has historically been used in other disciplines to denote plate-like structures, but there is no single universal definition applicable across all organisms. As a result, when the term appears in literature, it is important to consider the specific disciplinary context to determine what tissue or layer is being described.

Overall, lamellum serves as a descriptive label for a plate-like or layered region, with a well-defined role in the organization and dynamics of cell movement in certain migrating cells.