lamelle

Lamelle, in its general sense, refers to a thin plate, sheet, or layer within a larger structure. The term comes from Latin lamella, meaning a small plate. It is used across disciplines to denote a flat, sheetlike element that contributes to the organization or function of a system.

In biology, lamellae appear in several cellular contexts. In plants and algae, stroma lamellae are unstacked thylakoid membranes that connect grana and help organize the photosynthetic apparatus. In animal tissues, bone contains lamellae as thin, organized layers of mineralized matrix that form osteons in compact bone; these concentric lamellae contribute to the mechanical properties of bone. Teeth may also feature enamel lamellae, which are sheet-like structures within enamel associated with crack propagation in some conditions.

In fungi, lamellae are the gill-like plates on the underside of a mushroom cap. These lamellae bear the spore-producing surfaces, and their number, spacing, and arrangement are among the features used to identify species.

In materials science and geology, lamellae denote thin, layered structures within composites or minerals. Natural examples include the lamellar arrangement in nacre (mother of pearl), which consists of alternating organic and inorganic layers that enhance toughness. The concept of lamellae also applies to layered microstructures observed in polymers, metals, and crystalline minerals, where the thickness and orientation of layers influence properties such as strength, stiffness, and fracture behavior.

Overall, lamellae denote thin, plate-like elements that organize tissues, cells, or materials and influence their function and properties.