Cutikeln

Cutikeln (Swedish definite form of "cuticle") commonly denotes a thin protective layer found in animals and plants. The term is most often used for the soft tissue at the base of a fingernail or toenail, but it also applies to the waxy outer layer of plant leaves and the multi-layered exoskeleton of arthropods. In each context the cuticle serves as a barrier that protects underlying tissues.

In humans, the nail cuticle is a band of dead skin cells that overlaps the nail plate at the proximal nail fold. It seals the space between the skin and the nail, reducing pathogen entry and preventing moisture loss. Healthy cuticles are intact, noninflamed, and flexible. Damage from biting, excessive trimming, or harsh chemicals can lead to infections such as paronychia.

Plant cuticles are extracellular, hydrophobic films composed mainly of cutin and waxes that cover aerial epidermal cells. They reduce water loss, limit pathogen invasion, and affect gas exchange and surface properties like wettability. Variations in cuticle thickness and composition reflect adaptations to environment and stress.

Arthropod cuticles are composite structures of chitin, proteins, and sometimes minerals, forming a tough yet flexible exoskeleton. They provide mechanical support, protect against desiccation, and enable muscle attachment; molting allows growth.

Cutikeln, in its various forms, is therefore a multifunctional interface critical to protection, homeostasis, and interaction with the environment.