In
biology, the term cuticle or cuticula is given to a variety of tough but flexible, non-mineral outer coverings of an organism, or part of an organism, that provide protection. They are non-homologous, differing in their origin, structure and chemical composition. 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. 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. .
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