Cuticle

A cuticle /ˈkjuːtɪkəl/, or cuticula, is a term used for any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non-homologous, differing in their origin, structure, function, and chemical composition.

Human anatomy

In human anatomy, cuticle (sometimes confused with eponychium) refers to several structures. It refers to the layers of epidermal cells or keratinocytes that produce the horn protein keratin, and also to the superficial layer of overlapping cells covering the hair shaft (cuticula pili) that locks the hair into its follicle (See also Cuticle (hair)).

Invertebrate zoology

In zoology, the invertebrate cuticle or cuticula is a multi-layered structure outside the epidermis of many invertebrates, notably roundworms and arthropods, in which it forms an exoskeleton (see arthropod exoskeleton).

The main structural components of the nematode cuticle are proteins, highly cross-linked collagens and specialised insoluble proteins known as "cuticlins", together with glycoproteins and lipids.

Arthropod cuticle

The cuticle forms the major part of the integument of the Arthropoda. It includes most of the material of the exoskeleton of the insects, Crustacea, Arachnida, and Myriapoda.

Morphology

In arthropods, the integument, the external "skin", or "shell", is the product of a single layer of ectodermal epithelium. That layer is attached to the external or distal surface of the deepest layer, the non-cellular internal membrane of the integument. That non-cellular membrane is called the basement membrane. The layer of epithelium on the basement membrane produces the cuticle, which begins as a tough, flexible layer of chitin. Such thin, flexible chitin is the major structural part of the integument where flexibility is necessary, such as in bodily parts that must stretch to contain accumulated liquids, or that form joints between rigid parts of the exoskeleton. In other parts of the cuticle the function of the integument demands more rigid materials, such as armoured regions or the biting parts of the jaws, or where the exoskeleton forms the tubular limbs of most Arthropoda. To achieve such rigidity the outer chitin layer of the cuticle is impregnated, thickened, and reinforced with harder, more brittle materials such as sclerotinised proteins or calcite. This main chitinous layer of the cuticle is called the procuticle.

Cuticle (disambiguation)

Cuticle, or cuticula (Latin for "covering"), may refer to: