lamellae

Lamellae are thin plate-like layers or sheets that appear in many biological tissues, cells, and in some inorganic materials. The term originates from the Latin lamella, meaning a small plate, and is used to describe repeatedly layered structures of various kinds.

In animals and plants, lamellae occur in several contexts. In compact bone, lamellae are concentric layers of mineralized matrix arranged around a central canal, forming osteons. Osteocytes reside in lacunae between lamellae, and the alternating fiber orientations in adjacent lamellae help resist mechanical stress. In chloroplasts, lamellae can refer to the internal membranes that form grana and the connecting stroma lamellae, which participate in the light reactions of photosynthesis.

In fungi, lamellae are the plate-like gill structures on the undersides of mushroom caps that bear basidia and spores. In the skin, lamellar bodies are secretory organelles in keratinocytes that release lipids to create the lipid-rich barrier of the stratum corneum.

In geology and materials science, lamellae describe thin, layered features produced by deposition or processing, such as laminated rocks or layered composites. The term thus broadly denotes sheet-like subdivisions that contribute to the properties of the whole.

Lamellae is the plural form of lamella and is used across disciplines to describe any thin plate or sheet forming part of a larger structure.